To efficiently feed a non-resonant multi-band antenna.

### Antenna Mythology

#### Resonance

First, let's dispel the greatest myth in antenna theory: Antennas must be “resonant” to be efficient. Baloney! It just ain’t so!

Please recognize that an antenna need not be resonant in order to be an effective radiator. There is in fact nothing magic about having a resonant antenna, provided of course that you can devise some efficient means to feed the antenna. Many amateurs use non-resonant (even random-length) antennas fed with open-wire transmission lines and antenna tuners. They radiate signals just as well as those using coaxial cable and resonant antennas, and as a bonus they usually can use these antenna systems on multiple frequency bands.

—ARRL Antenna Book, Ch. 2

As long as the length of the antenna is at least a half-wavelength at its lowest intended frequency, its efficiency is well over 90%, just like a resonant dipole. The problem is getting power to it—coax is very lossy (due to dielectric heating) unless terminated into its characteristic impedance, and this effect is what leads many hams to erroneously believe that non-resonant antennas are inefficient. But the problem isn’t non-resonance, it’s high SWR on coax.

On the other hand, ladder-line does not suffer from high losses at high SWR, so may be effectively used to feed an antenna that may, at various frequencies, present the feed-line with any SWR from 1:1 to ~12:1. So, with ladder-line you can completely forget about resonance and SWR, until you get to the radio, where you use a tuner to make the match to 50Ω.

To compare mismatched feed-line losses we have to start with the antenna’s feed-point impedance, and the line’s impedance, then calculate the SWR, and finally, the loss of each feed-line-type at a given frequency and length.

For a worst-case example, feeding a voltage node (like running 40 meters on an 80 meter dipole), let’s say the feed-point impedance is 3500 ohms. With 100 feet of RG-8 coax at 7 MHz, that's a whopping 65:1 SWR, with a total loss of 78%. With 600-ohm open-wire line, the SWR is only 5.8, and the loss is 3%! Then, if we switch to 80 meters, the impedance is 50 ohms, the SWR is ~12:1, and the loss is 7%. In this case, 450-ohm line would be even better, because its characteristic impedance is closer to the geometric mean, so the SWR only varies from about 9:1 at 50 ohms to 7.7:1 at 3500 ohms. The total losses for 100 feet of 450-ohm windowed ladder-line, at 9:1 SWR, ranges from 5% at 3.5 MHz, to 14% at 28 MHz, and again, that’s at the worst-case mismatch points.

So we see that ladder-line is not only better for non-resonant antennas because of its much lower loss at high SWR, but also because its characteristic impedance places it nearer the geometric mean of the antenna's impedance range, from lowest (odd half-waves) to highest (even half-waves).

Handy formula: VSWR = (1+r)/(1-r), where r = (Zl-Zo)/(Zl+Zo), where Zl=load impedance and Zo=line impedance, in ohms.

#### Tuner and Balun Losses

Another popular myth is that antenna tuners are very lossy and waste a bunch of power. Baloney! A T-tuner, properly used, is about 95% efficient, and a switched-L tuner (like most auto-tuners) is about 98% efficient. If your tuner is getting hot, you have something wrong in the antenna system, and are exceeding the design limits of the tuner. A T-tuner becomes quite lossy when the antenna side impedance is low (<50Ω), but when it’s high (>50Ω) the efficiency is over 90%, reaching about 95% at ~500Ω. (See the graph at this article by G3TXQ ).

On the other hand, baluns can be very lossy, depending on the design and how they are used (or misused). As with tuners, if they are getting hot, they are wasting power, and you need to change the feed-line length (to move the anti-node out of the ham band), and use a balun designed for wide impedance variations.

Traditional baluns, such as the coax-wound toroidal 4:1 Guanella, are not designed to handle the extreme impedance variations of all-band doublets. They tend to arc or saturate and burn up at high power when presented with impedance extremes. Modern balun manufacturers have discovered this and now make 1:1 choke-baluns designed for ladder line feeds. Both DX Engineering and Balun Designs now make “tuner baluns” that are 1:1 current choke/baluns, and MFJ now puts 1:1 bifilar-wound choke/baluns in some models, like the 989D.

Many hams refuse to use it because they are afflicted by common misconceptions:

1. “Ladder-line radiates!” Baloney. Ladder-line does not radiate any more than does coax, if feeding a balanced antenna, like a center-fed dipole. If the power in each conductor is equal and opposite, we have complete phase-cancellation, and therefore no RF radiation. This is NOT true for off-center-fed antennas, like end-feed, or the various Windom-type feeds, where feed-line radiation is significant enough to warrant a bunch of power-wasting chokes.
2. “I tried it once, and it messed up my TV, my computer, and filled the shack with RF!” Again, ladder line should be balanced, and a good choke/blaun used at ot near the tuner. To further reduce common-mode current that may bring RF into the shack, make sure you use a length of ladder-line that is not a multiple of a half-wavelength on any band. Lengths like 40, 80, and 110 feet work well. A resonant length of ladder-line, just like the shield of coax, will pick up RF by induction from the antenna and re-radiate it into the shack. A non-resonant feed-line length will present a high impedance to common-mode current. And, as with any feed-line, it’s best to run it perpendicular to the antenna as far as possible so the magnetic fields from each half of the dipole will cancel each other instead of inducing common-mode current in the feed-line.
3. “It’s too hard to work with! You have to keep it away from metal!” Well, yes, a few inches or so. The general rule is: at least twice the width of the line. It’s easy to make stand-offs from small PVC pipe. Ladder-line can cross a metal edge, like a window sill; you just don’t want to run it right against metal for any significant length.
4. “It’s too hard to bring into the shack!” Baloney. There are many waterproof ways to bring ladder-line into any shack. You can drill two small holes through the wall and bring two #12-#14 wires through, then caulk, and connect them to the balanced output of your tuner. Or better, mount your balun outside the wall and come in with a few feet of coax. I like that way better because the coax is easy to disconnect (at a bulkhead fitting) during storms.
5. “It flops around in the wind, and it breaks too easy!” (a) Windowed line should be twisted about one twist for every two feet to prevent wind-induced oscillations. (b) Make a good feedpoint connection, with proper strain-relief. It doesn’t hurt to wrap the line over the top of your feedpoint insulator and then secure it to itself with cable ties. Also, the 14-gauge stranded is much more reliable than the 18-gauge solid line.

If you run an all-band dipole (with a tuner in the shack), you need ladder-line. Coax is very lossy when operated at high SWR. It’s easy to lose 75% of your power in your coax when operating on bands where the non-resonant dipole presents a high feedpoint impedance to the feedline.

#### Notes:

Continued…

1. Believe it or not, ladder line has much lower loss than heliax cable! It is great stuff, I have been using it for years. Don’t buy the expensive, 450 ohm stuff from the shops, it isnt very great anyway. Make your own 500 or 600 ohm line. Check out my QRZ (VK2AN) page for a very simple way to make it.

Ladder line should always have a few twists in it on the way down. If you dont have more than one twist/quarter wavelength, it will radiate slightly and pick up more noise. It is also quite tolerant of being close to other surfaces. I run it directly through a brick wall using 2 threaded rods with silicon sleeves. Mine occasionally flops onto the tin roof of the house, and I am amazed at how little difference that actually makes to the SWR.

Cheers – VK2AN

2. Hello Thanks for golden info for ladder line, I want a make 80 to 10 deltaloop with ladder line and 1:4 balun but i dont know 450ohm ladder line cable lenght ? its critical for me ?

• Yes, any time a transmission line has standing waves, length is important. You always want to avoid lengths where the impedance at the shack end is too high or low, in every band. See page 3 of this article.

• Harold, I am thinking of erecting an 80-10 Extended Double Zepp with an apex of around 45 feet. I have seen most say use a 4:1 current balun at the feed point but will 450 ohm latter line at the feed point down towards the ground (app. 40 feet) connected to a 1:1 current Balun or 4:1 current Balun work well fed by RG213U or RF8U to the tuner in the shack?

• No reason to use a 4:1 anywhere in a multi-band dipole. It will be mis-matched everywhere and lose all choking ability.
Brind ladder line down to a 1:1 choke at or near th tuner.
73, –kv5r

3. Hi Harold – I’m learning a lot from your Ladder Line articles (thanks!), and I have a question about a 80m loop I have put up at (unfortunately) only about 30 ft, feeding with a short (21 ft) length of diy ladder line, made up from #14 THHN and 4″ long spacers (TSC electric fence insulators).
After some pruning to ~254 ft total length, the loop tunes up well at 3.7 MHz (SWR 1.11, Z 56-j0.2) and 7.13 MHz (SWR 1.08, Z 54-j2.1), but it seems very “non-resonant” at 14.25 MHz (SWR 20.5, Z=223+j424).
My measurements are made directly at the bottom of the ladder line.
Why will the loop not tune at 14 MHz? Is it all about ground proximity effects due to the low loop height?

• Yes, earth proximity pulls the SWR dips away from their expected harmonic places. Impedance matching (for a low SWR) is not just “resonance,” it’s a complex number with reactance and resistance. The reactance varies with the length of the antenna, and the resistance varies with electrical height above ground, which changes with frequency. If you tune the length so 20M has a low SWR, them 40 and 80 will be off. At best, you can split the difference, or just use a tuner where needed.

• Thanks for confirming my suspicions re: the loop height. I will try varying the loop length to compromise the impedance at the desired 80/40/20m frequencies of interest, then let the tuner hopefully do the rest.

4. Assume such situation – trx – pa (vaacum tube) – antenna tuner – ladder line – doublet. In most PA’s schematics at the output there is Pi filter, so output is unbalanced I think. Which modification would be needed to ommit output Pi filter and “integrate” PA with balanced antenna tuner (balanced Pi)? So after this modification ladder line will be connected directly to PA – no coax, no baluns, etc. I’m sure somebody invented it earlier 🙂

• Hmm, after a while of thinking instead of PI filter I think it is possible to use link coupled tuner here. Primary coil on the PA side, and scondary side just like any other link coupled antenna tuner. It should work! I have to dig into old ham radio books and search for old circuits though…

• I suppose a two-tube amp, push-pull, with isolated outputs (neither one grounded) could be matched with a balanced tuner, but it seems pointless to engineer and build such a configuration, when an unbalanced (one side grounded) amp and tuner with a good choke/balun on the output will provide a balanced output to the ladder line (and be much safer to operate).

• Hi Harold
I am intending to use 450 ohm ladder line to feed my 36 foot “zero 5” vertical ground plane. Any hints? It does come with an 50 ohm un-un for coax Thanks

• No reason to unless you’re intending to use the antenna on bands it isn’t made for (high feedline swr), and an unbalanced load will unbalance the currents on ladder line and it will radiate.
If an antenna is designed for a match to coax it’s best to stick with it. But if you need to run a very long line (hundreds of feet), ladder line with a 9:1 balun on each end might be less lossy than a very long coax.
Just my thoughts. Feel free to experiment though!
73, –kv5r

5. Looking for input. I have a Tru ladder line ant system coming. Here is the proposed config.
160′ antenna (this is the room I have), 40′ at the apex, 15′ on the ends (inverted V) 37′ tru 600 ohm ladder line into a 1:1 (i also have a 4:1 just in case). My one problem is I have to run about 50′ of coax from the balum to the KPA1500. Bands of operation 75/80 and above. Will the KPA1500 handle this?

• I don’t know about a KPA1500, but 50 feet of coax will be VERY lossy with high SWR on it. Extend your ladder line and use 10 feet or less of coax between the 1:1 choke/balun and the tuner.

6. can you use ladder line to feed a zero five vertical ? the run of LMR 400 would be 75′ and im trying to limit my losses , can I lay ladder line on the ground ? or is that going to cause issues? im going through the wall with a 2′ piece of coax would like to know someones thoughts

• Verticals are generally designed for coax feeds. If your SWR is pretty low on the band(s) where you want to operate, ladder line will not improve anything, and will make matching complicated.
No, you can’t lay ladder line on the ground.
73, –kv5r

• Hello, this is N2MIR. I just bought a new G5RV. It is the more expensive model. It came with the balum. But I can only get it up 30 high between 2 trees. Some of the ladder line is on the ground with the balum. If it has to be cut how do I figure the right length? My only good swr is on 40 meters around 7.150. very frustrating since my very expensive auto tuner will not work any other frequency. Help!

• I don’t know about the ZS6BKW but if it’s like a G5RV the ladder line needs to be the supplied length, as it forms an impedance transformation at that length.
You need to get it off the ground though. Pull the middle out to the side with a string or something like that to take up some slack.
After that, if your tuner won’t tune it you need to ask its manufacturer.
73, –kn5r

• I had a G5RV for many years. It needed a wide-range antenna tuner to work any band. I now use a ZS6BKW. It performs magnificently. I bought mine from NI4L.com. It has approximately 40 feet of 420-Ohm window line. The window line needs to be off the ground and ideally suspended vertically below the feed-point. You must also use a minimum of 70 feet of coax to complete the match. I use LMR-400 with mine.

The SWR is under 1.5:1 between 29.6 and 29.7 MHz, and mine covers the 12, 17, 20, and 40 meter bands with no antenna tuner required. The SWR is generally below 2:1 and mostly below 1.5:1 across the 12, 17, 20, and 40 meter bands. With a wide-range tuner, other bands, such as the SSB portion of 10 meters, plus 15, 30, 60, and 80 meters are possible with the ZS6BKW. I use mine for 60 meters quite often. Mine performs very well on 15, 30, and 80 meters too. It is especially good on 15 meters.

The ATU in my Elecraft KPA-1500 amplifier can match any band that isn’t resonant, with the exception of 160 meters.

My ZS6BKW also exhibits a very good S/N ratio. I hope this information helps someone.

73, de N4HNH

• “You must also use a minimum of 70 feet (ca. 21 m) of coax to complete the match. I use LMR-400 with mine”

Sorry, but You match the antenna without coax. If made right, you didn’t need a coax match.

Nice to hear that the performance of ZS6BKW is better.

https://www.dl9nbj.de/zs6bkw-antenne/

• The ZS6BKW is not a form of the G5RV. Please do not mix everything. The ZS6BKW is the only one of the two that has resonance points on 5 bands. The ZS6BKW is an optimized G5RV.

https://www.dl9nbj.de/zs6bkw-antenna/

• the g5rv was initially a 3 half wave dipole for 20m band only.
g5rv experimented with the lengh of 300 ohm feeder, and short lengh of coax, to obtain a rough match on other bands.
its not a very efficient multiband antenna. the design goes way back.
the zs6bkw, appears to be an optimised version, that allows a decent match on more bands.
best 73 de bob. va3vs/gm0ley

7. I am too novice to say anything on the matter, but I cannot find anything about “There is in fact nothing magic about having a resonant antenna” On ARRL Antenna Book 23rd edition

• ARRL Antenna Book 21st, Ch.2 Antenna Fundamentals, Self Impedance, para.2, page 2-2.

8. This is a great resource! Owing to practicalities my proposed 51 foot doublet (40-10m) is arranged as follows: 31 feet of 300 ohm twin lead (ladderline?) to a 1:1 current balun and then around 23 feet of LMR400 to the shack and an unbalanced atu. The choice of LMR 400 is to try and offset some of the high swr prior to the tuner. I cannot bring the 300 ohm tany nearer the shack as the shack is right at the far right hand side of the antenna and would mean that the 300 ohm would couple with that leg and would need routing near the roof – leading to being near metal. My question is, to what degree do you think using low loss coax will compensate for not being able to get the ladderline any closer to the tuner? I see that LMR 400 has around 0.6db loss at that length for an SWR of about 7:1.

• Howdy Tim,
That should work fine. You might sweep the SWR at the end of the twinlead and see which band has the highest SWR, then calc your 23 feet coax loss at that freq and SWR, to see worst-case scenario. If it’s unacceptable (maybe, over 2dB), consider extending the antenna to 67 feet (even if 8 feet has to hang down on the ends), and extend the twinlead to near the tuner, thus making it a doublet. Just an option; it may be fine as proposed.
73, –kv5r

9. Due to losses in even the best coax, there must be a distance at which the installation pain/considerations of 450-ohm LL are worthwhile for 2m and maybe 70cm. I’m trying to determine what that distance is. But most importantly, I’m trying to determine the antenna system configuration for a 2m Slim Jim or J-pole (treated as balanced “dipoles in disguise”?) assuming I can protect the LL all the way to the feed point. ANTENNA – LL – BALUN/TRANSFORM/CHOKE – TUNER – XCVR? If this order is correct (even if it’s not), what type of BALUN/TRANSFORM/CHOKE device or combination of devices? Has anyone assembled an effective efficient 2m antenna with LL as the feed line? Very intrigued by this LL thing.

• Yes, 1″ window line can be used on 2 meters. It’s too wide for 70cm though (the 1/2″ LL might work on 70, I donno). Many years ago I built a 10-element yagi for 2 meters and designed it with a 390-ohm asymetric folded dipole as the driven element. At the radio end I built a very simple L-match. It worked great!

Your order of things is correct.

You’ll need to find a good 1:1 choke/balun design for VHF. Probably just a few turns on a type 43 toroid, but I don’t know. Ask a balun designer what ferrite mix & turns count will have high common-mode rejection (CMR) at 2 meters. A balun for HF will have little or no CMR at 2 meters. Don’t try to transform impedance with the balun – use a simple 1:1 bifilar (2-wires) wound on a toroid. Let your vhf L- or T-match “tuner” bring it down from 400 to 50 and let the balun just be a choke.

On a j-pole, I suppose you could use a nanoVNA to locate the 400 ohm point on the J stub, it will be well above the 50 ohm point where you’d normally connect coax.

Or easier, just make a vertical folded dipole out of a piece of the same window line and hang it up or tape it to pvc pipe.

73, –kv5r

• More info. I did some study of common mode chokes at 2 meter. 2 turns (passes thru) a type 31 toroid is best. More is not better; 3 turns moves the peak common-mode resistance (CMR) way down lower in frequency.
If you don’t want to use a toroid, use 5 turns around a PVC pipe, works, but not as good as a toroid choke with the peak CMR at the right place.
73, kv5r

10. Hello Herold, I am writing to you from the extreme south of Brazil and I am fascinated by the wealth of details you have spent. I will look on your website for some way to send a contribution to keep it up.

Well, I built a ZS6BKW with 14.25m each element and the open line with 12.46m. Initially the project I found was 13.75m each element and 12.20m the open line, as I was undecided and afraid of not being able to adjust it, I built it by the largest measure and I adjust it.

my question is in relation to the balun, which one to use because here in Brazil these antennas are not very common, most of the hams use common dipoles.

I see a lot of comments for using 1: 1 or 4: 1 and also 9: 1 … I don’t know what to do … I have the need to use approximately 15 to 18 meters of cable up to my TX and between the LL and the coax I must use one of these baluns.
There was a US colleague who indicated the 9: 1 balun and that would be ideal, but another colleague indicated the Guanella balun. One last question would be about the toroid, if using the T200-2 or FT240-43 to operate with 250w of the TS480HX and eventually a 500w amplifier.

Forgive me the immense text, but I have collected all my doubts.

73 and may God give you health, wisdom and stability.

• Hello Vinicius,
You need a 1:1 current balun for the ZS6BKW design. The ladder line section transforms the impedance to near 50 ohms where the coax connects, on the bands it operates, 40 20 17 12 10. On other bands the SWR on the coax will be very high and very lossy. For this reason, I prefer no coax, but build an 80 meter dipole and ladder line all the way to the shack and use a 1:1 choke/balun and a tuner on all bands 80-10. This is better than having 3 bands (80 30 15) where the coax loss is very high with the ZS6BKW design.
Do not listen to hams who say you must put a 9:1 between 450 and 50 ohm lines. They do not understand the difference between matched-line characteristic impedance, and and using an un-matched line as an impedance transformer. A 9:1 would only be correct when the ladder line is terminated into a 450-ohm antenna, like a 3-wire folded dipole, used on 1 band at resonance (450j0 load on 450-ohm line).
Here is a good paper on the ZS6BKW – http://w5ssv.com/resources/The-ZS6BKW-Multiband-HF-Antenna.pdf – you see he uses a 1:1.
For the 1:1 balun, you will decide if you will prefer lower bands, use type-31, or upper bands, type-43 core. These are simple to build, with a FT240 core and about 11 turns of teflon coax (RG400). I think 1 core is good for 500 watts, but use 2 cores stacked, for higher power.
Vy 73, –KV5R

• Hello Harold, here is Vinícius again…

See this choke 1:1 50R to undefined impedances.

https://www.wolfgang-wippermann.de/balun1zu1undefgross.pdf

researching deeply about chokes, baluns and the like, I came across a video of this German Radio Amateur, where he explains that the most suitable for meetings of coaxial cable and ladder lines is this project that is on the link.

thanks again and we keep exchanging ideas.

Greetings!

Vinícius – PY3VI

11. Very helpful rabbit hole here. Thank you kv5r and contributors. I am looking to deploy a 132’ doublet fed with window line. Would I benefit by building it as a fan dipole with a 20 meter half wave element to get better performance on say 20, 17, 15, 12, 10 meters.

Yours Craig, w7phg

• Howdy Craig,
I’ve wondered the same thing, but I really don’t know. I don’t think so. The shorter dipole will have less lobes and nulls on the higher bands, but most of the power will still go to the longer one.
Fan dipoles are typically multi resonant, and fed with coax. The coax “selects” the one that has the best impedance match, near 50 Ohms, at a given frequency. Feeding with ladder line, all the dipoles will be mismatched, so the power will not “favor” the one intended. So you’d need a relay, or two feed-lines, and run the dipoles crosswise, so one antenna doesn’t soak up the other on transmit.
73, –kv5r

12. Good afternoon. I’m a new ham. In my search for information I had the good fortune to stumble upon you website. Added to my favorites.
Started out listening in on a Sears/Yeasu FRG7. Going the hybrid/old school route with a Kenwood TS 820s, with matching tuner and remote VFO. Picked up at a reasonable price, used, not abused. Sent the radio out to a subject matter expert (K9TW) for cleaning, re-capping as needed and re-alignment.
Starting out with a ZS6BKW antenna w/1:1 Balun. Going to set it up as an inverted “V” about 35-40′ high in a nearby tree. Is it better to run the feed line at an angle from the apex to my 2nd floor window where my station will be, attached with a short length of coax thru a lightning arrestor and bulkhead connector at my window to my radio or let the feed line hang straight down run along the ground a short way, then up a longer length of coax to my window?
Thanks, Dan G.

• Howdy Dan, welcome aboard!
It’s “best” to run the feed-line perpendicular to the antenna, and that need not be straight down but can swing out to one side. In practice, any angle is okay as long as it’s not nearly parallel to one leg of the antenna. Keep the coax as short as practical.
73, –kv5r

13. Dove posso trovare distanziatori a clip in uso al mondo agricolo / giardinaggio?

In Italia se possibile.

Grazie

• “Where can I find clip spacers used in the agricultural / gardening world?”

In Italy, I don’t know. In USA there are “Zareba” and “Fi-Shock” brands of 4 inch “ribbed tube insulators.”

• What I have found here in the states is a pipe called shark bite pipe found in garden shops such as lowe’s , home depo etc comes in different diameters and cheap ( \$1.88 for 5 foot length ) I chose the 3/8 od size plus it is uv ok k6iy

• Yes, there is also “PEX” tubing. The 3/8ths-inch would work nicely. The rolls have a curl, but some places (Ace Hardware, here) have it in straight 10′ sticks.
3/8″ tubing would allow for wider (1/4″x11″) Ty-Raps, which are much stronger than the 1/8th” needed with the smaller ID ribbed-tubes.
–kv5r

14. Harold,
Your willingness to share your deep insights of the different areas of your interests is greatly appreciated. Your website is more helpful than many books I have bought as amateur radio reference material over the years. I have sent you a donation to help keep your material available not only to me but to others as well.

I started trying to get a ham license more than forty years ago. I passed the Novice theory part of the test back then but never did go back and take the 5 wpm code part. Life sort of got in the way and many years went by. I stayed active in SWL all those years and dreamed of “some day” getting my ticket. Last January I decided to do it. I studied a couple of weeks and took all three tests on the same day. I passed the Tech and General but fell short of the Extra. As my main interests are in the 160-40 meter bands I’ve bought an old Kenwood 520SE boat anchor in pristine condition, a Drake MN2000 tuner, an almost new Acom 1010 amp, and an MFJ259B analyzer along with several other related accessories. I still have not gotten on the air yet as I’m working on an antenna about which I wanted to ask you a couple of questions.

I’m putting up a full wave 160m loop but due to age (and XYL) I can only get it about 20 feet or so above the ground ‘cause that’s as high as I can climb a ladder. I realize that it may be better at NVIS than DX but that may be the best I can do for a while. I have enough real estate (and NO HOA!) that I can later erect a 20-10m loop if I decide to work those bands much. I plan to cut the 160m loop so it can be used on multiple bands if my tuner will handle it. If I understand correctly the length should be 1005/1.75 – 4% (insul wire) = 551’. I plan to feed it with 14ga 1” window line to my shack and convert to LMR400 to bring it into my shack which brings me to my questions.

My corner feedpoint is about 40’ from the point that I would need to install a balun to change to coax. Is 40-45 feet acceptable as a 1/8wl multiple on the lower bands? Should I use a longer length and loop or zig-zag it?

I would need about 20-25 feet of coax from the balun to get to my radio inside my shack. Should the odd 1/8wl rule apply also to that length of coax? If I need a longer length can I just loop it inside the shack?

Also, I’m a bit confused about the correct balun to use. I understand and agree with your reasoning for suggesting a 1:1 balun in situations like mine. However, I was told by a balun manufacturer that I needed to use a 4:1 balun since my MN2000 tuner needed “a little help” in his words. I realize the MN2000 is not a “modern” tuner but is it built so different that it needs a different balun in this application?

Your advice and expertise would sure be appreciated and might be helpful to some others in a similar situation as well.

73s
KO4BIQ

• Yes, the total feed-line length (ladder-line, balun windings, and coax) are all transmission line, and the total length needs to avoid quarter and half-waves.
Use a 1:1 current balun/choke. A 160 meter loop 20 feet high is gonna have a real low feed-point resistance, and you don’t wanna lower it further by a factor of four. Be sure to get a 1:1 “ATU” or “Tuner” balun. Regular baluns lose their choking ability when running in a high SWR line (and tend to burn up).
Looking at the Drake (MN-2000 schematic, it’s a T-network (high-pass) tuner, which will be very lossy at low impedance, and very efficient at high impedance loads.
With high SWR on the line, the impedance the tuner sees depends on frequency and line length. It has nothing to do with the “characteristic” impedance of the feed-line. Using a ratio balun (like 4:1 etc) does not “help” any tuner (it’s a myth) — well, it may help at some frequency, but hurt at most other frequencies (according to the extensive engineering work by G3TXQ).
Just plan for several extra feet of feed-line so you can remove half of the extra if you have a band that won’t tune.
73, –kv5r

15. Hi, Harold! I’m contemplating running a G5RV or 100 to 120 foot dipole for 80-10 meter operation, possibly OCF, only about 20 feet in the air between trees and alongside my house, fed with ladder line. Any preference for 300 vs. 450 ohm for the ladder line? Also, due to restricted space the ladder line will probably need to come down and then travel laterally to the outdoor 1:1 current choke and auto tuner, essentially traveling beneath)(so parallel to) the antenna instead of perpendicular to it. Should that be a problem?

• That should work okay. Paralleling the feed with the antenna will induce some common-mode current on the feed-line, upsetting the balance and the pattern to some degree, but a good 1:1 choke should cancel most of that.
300 or 450, your choice. The 450 will have a bit lower loss, particularly when wet.
I wouldn’t run it OCF, as that severely unbalances the feed line and it radiates and messes up the pattern.
73, –kv5r

16. I want to improve an existing end fed wire in an attic used only for shortwave listening. Receive only. No transmitting. The length is 43 ft fed into a vintage tube receiver using 75 ohm TV coax. The radio has a high impedance balanced input. What I want to do is cut the antenna wire in half so as to make a simple dipole and then feed that dipole with ladder line straight to the radio.

Should I also consider a 1:1 choke? I presume I will not need any balun given the radio’s input.

• I’d try first modifying the twin lead with stranded single wire into a 70 feet long piece and split it into a single 70 feet of wireand fold it into a folded dipole by using wooden dowels about 6 inches long for speaders only 35 feet long and install a 6:1 transformer onto your twin lead where the 75 ohm coax if you really need a 6:1voltage balun. I’d probally use the shortest jumper of a coaxial parallel to the folded dipole

• If you center-feed the wire with twin-lead, that could go straight to the radio without a balun, although running a 1:1 choke at the radio end might reduce in-house noise picked up by the feed line.

17. In regards to window line, is it possible to cover wl with copper pipe foam insulation then slide it into the proper size white plumbing pipe for burial in the ground. I feel this would keep the wl centered in the pipe. Just a thought as i have to go from my gap vertical 103 feet to the side of the house than 20 feet to my tx.

• Yes, it’s possible; the question is what would the dielectric and inductive losses be. The pipe insulation is usually a closed-cell foamed PE, at a much lower density than what’s used in coax, so it might be OK. Inductive losses to ground will depend on the width of the line and diameter of the pipe.
If I were able to do such an experiment, I’d probably use half-inch (300 ohm) window line in 2 or 3 inch pvc thin-wall sewer pipe.
Ideally, you’d run the line above ground on poles and measure the loss (almost none), then pull the line underground and measure again (both over wide freq & SWR ranges). To my knowledge, no one has done this (for more than 10-15 feet to get out of a basement), so if you could do such a test it might prove valuable to many hams.
On the other hand, your GAP antenna should have resonances in several ham bands, so why not just use direct-burial coax?
73, –kv5r

18. Hi Harold,
Thanks for your website full of info and especially for your responses to my comments and questions. I learned a great deal about the use of LL from the experience, but I’m setting it aside for awhile. The reason is that after all these years I hit the jackpot and found the antenna with the performance I always wanted….my dream antenna. I can hardly believe it.

I could have built my own antenna and saved some money (my usual approach), but here in Arizona the Sun eats everything and I had to defer to durability of materials and longevity. Consequently, I purchased the commercial version of the Cobweb antenna and raised it to 35 ft. agl using TV mast and dacron guy ropes. It only weighs 4 lbs. so I could get away with that. I’m feeding it with quality low loss RG-8/U and running 100 watts. I want less loss when using my MFJ-949 to match it at the band edges, hence the lower loss coax.

I may need to take some foreign language courses, or at least brush up on understanding English with accents because this antenna is like no other I have ever had. I am even able to work these foreign stations in 20 meter pileups and get 5/9 signal reports. Also, I can hear all the other stations like never before. I still use LL to feed a doublet for 40 and 80, and may get around to trying the square folded configuration. Thanks again and 73

• Hey Russ, that’s great!
I’m wondering if you got far enough with the LL-fed square-bent dipole to compare it’s performance with the cobweb?
Or, what problems, if any, you ran into with the former?
I still want to build one, if I can manage it, and do an article on it.
73, –kv5r

• Howdy Harold,
I was able to erect a square folded doublet with a length that resonates at 6.5 MHz because I didn’t have room for a larger square. The quick result was that the dang thing wouldn’t tune well when fed with LL. I think the feed point Z is just too low for LL to be happy. I tried shortening the LL checked tuning, and then lengthened the LL and tuned again with no noticeable improvement. I now think this configuration could benefit from an auto transformer to raise the feed point Z. Maybe even a 16:1 ratio? I don’t have enough knowledge in that are to know what to try, but maybe you do?

That’s when the shiny cobwed caught my eye and I have been hypnotized since. I would like to know if you give it a try! 73, Russ

• Harold,
I should tell you that I started at the beginning. I used a single wire for the folded doublet and fed it with LL. If you take up this quest, I suggest you start with the folded dipole model you had described. Maybe that configuration will make the LL happier? 73, Russ

19. Hello,
Very nice reading. Just to clarify some thought on my setup
I have a 265 foot loop at about 60 feet, fed with ~600 ohm open wire line.
I have the MFJ 998RT 1500w auto tuner (coupler) at ground level.
Questions
1) what would you suggest for feed line length. 80-90 feet?
2) what Balun should I use at the auto tuner. 1:1, 2:1, 4:1…
The tuner has a wire line input but according to the schematic there is no internal Balun it just gets fed right into its C-L-C Pi network.

• Howdy George,
80 meter loop at 60 feet, that’s gonna be great!
1. Yes, 80-90 should work. I’d start with ~98′ in case you need to trim it to make the tuner happy on some band.
2. I’d use a big ol’ 1:1 choke/balun like the Balun Designs 1171. Better the impedance be high than n/4 lower, and the 1:1 has much better common mode choking than a 4:1 does when used in that wide impedance range scenario.
73, –kv5r

I just ordered the Balun Designs 1171. I do have a 1:1 choke Balun (balanced on one side and unbalanced on the other) but its just a piece of coax rapped around a ferrite core.
I suppose the length of the open wire line/ladder line at ~98′ does not depend on if its 450 or 600 ohm or anything in between.
Again Thanks
73 N1naz

• No, the characteristic impedance of the feed line has no effect on its electrical length. Only velocity factor does. And the length isn’t critical; and even characteristic impedance is meaningless except when a line is terminated into same impedance.
73, –kv5r

20. OK Harold, I’m pretty sure we can feed this square bent doublet using LL, balun, tuner, but before constructing a prototype, some important questions should be answered. I have found lots of material on regular doublets and how height agl affects radiation take-off angle and that it varies by frequency. I could only find limited information about the Cobweb design (where this started) about toa, save it is 37 degrees and not dependent on hagl or frequency. I wonder if 1) toa will vary with frequency in the frequency agile square bent doublet? and 2) if the much lower noise pickup characteristic of the Cobweb design will be still present in the square bent doublet? Could these two performance attributes of the Cobweb design flow from the fact that the loops are resonant? What do you think?
73, Russ

• Well, I donno about their takeoff angle versus height claims… Any horizontal antenna will have a low elevation angle at half-wave high; it’s a matter of it interacting with ground reflection, and as far as I know resonance plays no part in that. Resonance is simply opposite reactances cancelling out, which affects the feed-line, not the radiation pattern of the antenna, which is a function of shape, height, and ground characteristics.
The original cobweb designer made claims that I consider somewhat dubious, about ground interaction, lower noise, etc. It has less ground interaction (than a straight dipole) because it covers less ground. As for lower noise, if it does, then it’s less efficient. It’s not a loop, and even loops are not actually quieter (better S/N) than dipoles. I seem to remember someone saying it’s quieter than a vertical, but that’s because local man-made noise tends to be vertical and it’s horizontal, not because it’s bent into a square. IMO.
Anything you can learn about it from actual experimentation will be breaking new ground!
73, –kv5r

21. Howdy Harold, Thanks for the reference article and your ideas. When feeding the “square bent doublet” with coax I put a 1:1 balun at the fp because I was going from unbalanced coax to balanced folded dipole. So to feed with LL instead of coax, should I omit the 1:1 balun? Thanks for your advice!…Russ

• Yes. A choke at coax feed-point breaks the “3rd-wire” (the outside of the coax) current. With LL, there’s no 3rd-wire, but induction from the antenna puts common-mode current on both wires, so the choke is needed at the shack end, to present a high impedance to CM, so it can’t flow. So a choke is always needed at the FP for coax, or at the shack for LL.
Keep in mind, a “balun” is really 2-3 things. 1) A common-mode choke, 2) a differential-mode current balancer, and 3) if it has a ratio other than 1:1, an impedance transformer. It can perform each task with varying effectiveness, depending on (at least) three things: 1) its design, 2) how well it’s matched (on both sides), and 3) both 1&2 swept over some frequency range.
With non-resonant frequency-agile antennas, high SWR on the feed-line turns it into an impedance transformer, which presents the balun (and tuner), at almost all combinations of LL length and frequency, with either low-Z (high current) or high-Z (high voltage) challenges. Hence, the need for baluns specifically designed for both wide bandwidth and wide impedance range.
Coax is not inherently “unbalanced”, indeed if it isn’t balanced, it will radiate, i.e., it goes from transmission line mode to antenna mode, to the degree it’s unbalanced. But it IS imbalanced by the 3rd wire (outside of the coax), which has one end connected to half the antenna, and the other end to ground. That (alone) is what makes it “unbalanced,” assuming the load is balanced.
So, using a balun is isn’t simply a matter of coupling something “unbalanced” to something “balanced,” it’s a matter of blocking undesired currents, either 3rd-wire or common-mode — in addition to balancing differential mode currents.
Another common misconception is that transformer baluns must be used to couple lines & devices with different “characteristic” impedances, which is only true when lines are terminated into their characteristic impedance, which only happens at one frequency. But with frequency-agile systems, a “450-ohm” or “50-ohm” ohm line, well, just isn’t. The mis-matched load (and resultant standing waves) turn it into a “variable-ohm” line, i.e., a linear transformer. That’s why “length doesn’t matter” is only true at 1:1, while it matters very much on high SWR lines.
Anyway, I better quit rambling on for now! 🙂
73, –kv5r

22. Harold, this IS going to be fun! The loop easily tuned to 14.25 MHz. I was talking on it with a station in Atlanta. He reported my signal was stronger on it than on the G5RV. A few minutes later I heard a station calling CQ DX. I assumed it was a state side station because it was so strong. Nope, JA8COE Taka was in Okata Japan and he told me my signal was 5/8. He could not hear me on the G6RV.

My test loop is at 10 feet and the fp is just a few inches off a stucco wall on the East side of the house! I wonder what this antenna could do if up and in the clear. LL or no LL, this is a huge success!. 73, Russ

23. Update: Harold, I put up just the 20 meter loop in a square 10′ off the ground so I can work with it. Starting from the beginning of this quest to eventually feed with LL, it is fed with 20′ of RG-58 and an air core balun 1:1 is at the fp of this folded dipole of # 16 speaker wire. The fd has shorts at 8 feet from the fp on each leg. Low and behold the SWR is 1:1 at 14.809 MHz and increases on each side of this freq, giving a 2:1 bandwidth of 200 Khz. So, next I am adding wire to lower the freq to 14.250 Mhz. Good to know the fp impedance is 50 ohms, which is easier to wk with. After playing with it this way over the weekend, next step will be to add a 4:1 balun with the hi-Z side connected to LL.

• Howdy Russ,
Looks interesting. I’m guessing you read the article of the original G3TPW CobWebb to get the idea of speaker/zip wire and shorting links moved way in. I guess that works but not really optimal folded dipole; the TL mode impedance of zip wire is about 110 ohms and the VF is about .66, which is why the shorts must be so far in, to compensate for a big “stub” effect. Please read this G3TXQ article on folded dipoles, he explains all that very well.
Since the goal is to make it a nonresonant ladder line fed antenna (let’s call it a “square-bent doublet”), designing around resonant points and SWR goals is sorta meaningless. Everywhere (even at its resonant point) will present a high SWR on ladder line, which thus becomes an impedance transformer, varying all along its length, so the final impedance presented to the tuner might be anything from ~10-4000. As with straight doublets, trimming the ladder line brings it to within range of the tuner (hopefully).
I think if I built one (and I may if I can manage it) I’d make a 3-wire FD out of #17 aluminum (electric fence wire) and space them ~4″. That should have ~500 ohm TL mode imp and a VF ~.95, which according to the above G3TXQ article will not need any moving in of the short, and at resonance about 450 FP imp. The overall width of 8″ would also increase the bandwidth of the dips, altho at 10 meters it’s a 1-WL ant and FP imp will be extremely high, nowhere near dipping. Again, LL of the right length can transform that down to a tunable value.
Tees on the ends of the spreaders would allow separating the 2 or 3 wires vertically a few inches.
Anwhoo, just some random thoughts. If this idea works, it’s gonna be fun!
73, –kv5r

24. I have an inverted V, apex at 65′
Each leg is 117′ fed with:
63′ of 600 ohm home made open wire feed line –>
Model 4114 – 4:1 Current Balun 1.5 – 54MHz 5kW –>
MFJ994B tuner –>
ALS600 Amp –>

The only thing is, Robert at Balun Designs recommended his Model 4114 – 4:1 Balun for this antenna and everything I have been reading lately says it should be a 1:1.

It, as of today tunes on all bands up to 10 meters. It even works on most of 6 meters.

• Yes it’ll work fine; people been using 4:1s on such antennas for decades. But the newer info about using 1:1 on multiband LL-fed doublets has been well-established by G3TXQ (see here), and W8JI (on the DXE site). There is 2 issues. One, T-match (CLC) tuner efficiency goes way down at very low impedance, so in most cases it’s better to not further reduce by 4 (see the tuner efficiency graph in the G3TXQ article); and two, 4:1 current baluns tend to lose most of their common-mode choking ability when badly mismatched, whereas the 1:1 bifilar-wound-toroid choke does not. (sorry but I’ve lost my reference to #2 issue, prolly W8JI article tho.)
73, –kv5r

25. I should have written when the folded dipole is made into a circle like the cobweb ant. I’m getting older, too!

26. Harold, Sorry I forgot to mention your folded dipole idea. That might get the fp impedance up to about 50 ohms which maybe could be fed with LL and no balun. I’m using a normal fp impedance of 200 ohms for a regular folded dipole becoming 50 ohms when folded.

27. Sounds good. I will give it a whirl and let you know. A few followup questions: Since we use LL to feed a dipole that is resonant or nearly so on 80 meters (the 80-10m doublet), LL sees a 50-70 ohm fp at that freq. So, if I use a 4:1 balun to up the fp impedance from 12 or so ohms to 50 or so ohms, I figure the LL could feed it OK? Of course the fp impedance would vary w/freq. but in the cobweb it would be low. What about a 9:1 balun instead to raise up the fp impedance even higher? Any ideas on this?

28. I just became aware of the Cobweb antenna design while looking for a lower takeoff angle like a vertical. Thanks to you, I recently learned a lot about LL and now have it in service to a G5RV.

I was wondering what you think about a horizontal loop antenna fed with LL? The Cobweb boasts a low radiation angle, but it is tuned to resonance and fed with 4:1 balun to coax. Would a non-resonant loop have similar characteristics? If so, could it be fed with LL to the shack balanced tuner?

Thanks again and 73,
Russ

• I’ve had that very thing in mind for a long time — a dipole bent into a square fed with ladder line for 20-6. But I’m too old to build the damn thang. Prolly make it a folded dipole as the fp imp gonna be low..
Give a whirl and let us know how it works!
73, -kv5r

29. Is PVC pipe a friend or foe to HF LL? I read about using PVC pipe as spacers and standoffs,but also read don’t enclose LL in PVC pipe.

I use 12″ PVC standoffs for LL running along a stucco wall to the shack, but up top, the last 10 feet of LL that connects to the center insulator of my G5RV is inside a 1-1/2 inch piece of white schedule 40 PVC pipe. Is that a no-no? I’m thinking a metal mast with LL on standoffs would be better, but worth the effort?

• Well, PVC has a rather high dielectric constant, but I doubt 10 feet will cause any noticeable problem. Indeed, it may be less lossy than having a metal mast nearer the antenna.
73, –kv5r

• I have a couple more myths for you.
“300 Ohm twin lead won’t work on UHF tv frequencies”
FALSE The FACT is twin lead has lower loss on UHF tv frequencies than RG6.

“All tv antennas are now 75 ohms”
FALSE The FACT is that nearly all tv antennas are still 300 ohm antennas that now must use a lossy balun to use coax.

“Twinlead leaks and is more prone to interference than coax”
FALSE The FACT is balanced line does not “leak” signal
or create interference issues on TV.

30. thank you sir for your work I consult you .. a wire of 41 meters fed 12 meters from the tx with open line to an L coupler outside the cabin and from there 6 meters of rg 213 ?? What he thinks is to work all the bands.

• Yes, that should work well. As always, a small change of the ladder line length might be needed if one band will not tune.
73, –kv5r

31. Hi Harold, I really enjoyed your website, particularly the articles on the use of ladder line and other balanced feed systems for multi and operation. I have been a big proponent of these types of antenna systems for many years and have learned a lot from reading W4RNL, W2FMI, W2DU and many other experts.

I have also learned from you. I found your website from a search of antenna feedline lengths to avoid and I really like the simplicity of the “odd-eighths” formula. I am applying it to my new 130′ doublet, which is fed by 300-ohm window line as part of a stealth installation.

One thing that I am surprised to find missing is the use of a remote antenna tuner or coupler. These simple-to-use devices, along with a good current balun, make the antenna system a matched, balanced system that is efficient on many bands while reducing clutter in the shack and providing solutions to situations where one cannot run balanced line to the shack.

For instance, I ran coax underground from the house to my shed, connected it to my SGC-231 and balun, then to true ladder line to the antenna feedpoint. At 70′ height, that was the best antenna I’ve ever had.

My current installation involves the balanced line running into the attic, where the tuner and balun reside. From there coax to a Single Point Ground System (SPGS) box (see Ward Silver’s excellent book on Bonding and Grounding) which connects to the radio in the shack.

Well, that’s the world according to K4FAN. I hope it gives you readers some other ideas to go along with Harold’s. Good luck with your antenna projects and 73 de Eric.

• Howdy Eric,
Thanks for the flowers. Yeah, remote tuners are great, but way too expensive for me (particularly the legal limit ones), so I haven’t said much about them. This site has always been about keeping things simple and costs down, which is the end of the spectrum I know best… 🙂
Aside from cost, the only thing I wouldn’t like about a remote auto-tuner is its vulnerability to lightning impulse damage. I know of one ham that built a remote switch with a linear actuator and copper pipes — he can push a button and open a 2-foot air-gap at his remote tuner!
73, –kv5r

32. I’ve just read though the info on ladder line use, but am a bit confused of how to apply it to my situation. I have a G5RV installed with the supplied 32.5 feet of 450 ohm LL dropping down to the outside wall of my stucco house with standoffs, and the radio shack directly on the inside wall. I removed the coax feed line that is normally used with G5RV, because of losses on bands other than 20M, and run the LL into the tuner. I’m only running 100 watts from an IC-718 through an MFJ-949E versa-tuner. I’ve drilled 2 holes an inch apart and mounted a small wood block on each side of the wall to hold bolts w/nuts, and #14 insulated solid copper wire to connect outside to inside bolts,then 2 of the same wire from inside bolts to balanced output of the tuner.
Q: Do I need a current balun outside the house, then coax through the wall to the tuner, or will the above setup work OK?

• That’ll work fine. I ran LL all the way in to a 949E for several years, then replaced that with a 993 autotuner.
Current setup here is an outside balun and coax jumper to a grounded bulkhead fitting, just because it’s easy to disconnect for storms.
73, –kv5r

• Thank you for confirming my setup as I have never used LL feed lines before. The MFJ-949E will match on all bands 75M-10M,but after recording all the settings I noticed something unusual. The settings for 40M and 20M are nearly identical (5.5,I,0) and (5,I,0) respectively. I hope this just means the impedance presented to the tuner is about the same and doesn’t indicate something is wrong?

33. With regard to ladder line, open wire, etc. and the old adage to run the feedline away at a right angle to the antenna for as far as possible, does it matter whether it goes straight down then over, straight out at height then down, straight over angling down, or a combination such as sagging down and over … to the entry panel?

They all work and maintain balance with respect to the halves of a dipole, but have different relationships to the antenna.

For instance, with an inverted V on a single mast, it is both practical and useful (top loaded vertical, etc) to run straight down the (non-conductive fiberglass) mast, yet this places the ladder line directly under the high current point of the antenna, albeit with a small profile, as well as closer to the antenna’s elements (being in the center of the 90 – 120 degree aperture of the V) … all this relative to the other possible routings of transmission line.

If the goal is to get it away from there as fast as possible, then a straight run at 45 degrees M/L downward makes sense and the feedline could also be used as a ‘guywire’ if properly secured and rigged.

I’ve used all of the above at one time or another and they all seem to work fine. It seems the 90 degrees to antenna is the most important point (in maintaining balance) but is there some other worthwhile consideration as to “how” you route the 90 degree line from feedpoint to station?

Thanks, Jim

• Howdy Jim,
You can come away from the feed-point at any angle around an imaginary disk that’s perpendicular to the antenna. So, the line can go down, or out horizontally, or angled, or even swagging from vertical to horizontal, as long as it’s perpendicular to the antenna, i.e., not closer to one end than the other.
The idea is that RF induction onto the feed-line is minimal where the fields from each side of the dipole are opposite and equal, so there’s no common-mode current induced onto the feed-line. I don’t think it matters if the dipole is straight or inverted vee; there’ll be that phase-cancellation null “disk” around the antenna where the fields cancel (assuming the antenna is really symmetrical and balanced).
Of course, having the entire feed-line perpendicular is an ideal, and in reality it’s seldom practical to bring a perpendicular feed-line all the way to the shack. Fortunately, the field strength diminishes by the inverse cube of the distance, so the perpendicular part doesn’t really need to be like a half-wave, but 30-40 feet perpendicular, with the remainder angling away, will work fine.
And as always, a 1:1 choke at the feed-point for coax, or at the shack for ladder-line, blocks most common-mode current, making feed-line routing less critical.
73, –kv5r

• Thanks, makes good sense.

1 – so this applies equally to coax as well as ladder line?

2 – how about the case of center-feeding a half wave inverted L (at the top, without ground reference) where a perpendicular ladder line balanced with respect to the two legs is awkward and very difficult at best?

Something I’ve wanted to try but haven’t figured out how to route the transmission line.

73 -Jim

• 1. Yes, sorta… With coax, current induced on the outside of the shield and doesn’t affect the currents inside. With LL, common-mode current induced on both conductors affects the differential-mode currents thereof. In both cases, a choke inserts a high impedance that blocks the common-mode, without affecting the differential mode.
2. I suspect that a center-fed dipole erected as an inverted L will have a phase-cancellation null shaped like a disk at a 45 degree angle (looking from the side) and the feed-line could still exit anywhere along that disk — straight out to the side, or down 45 degree line mid-way between the ends of the antenna. Of course, such an antenna would be badly imbalanced, because one end is close to the ground, so it would be hard to determine where the null-plane is. Mid-fed slopers have the same imbalance problem.
I think the best answer to all this is, (1) use a good choke at the right point, and (2) don’t run feed-line close to one side of the antenna.
73, –kv5r

34. I have room to string a rectangular loop in my attic (above 2nd story), 10’x40′, and hung using some antique screw-in stand-offs with ceramic insulators. Feedpoint will be at center of one short side and the bottom of the louvered vinyl vent, which has fiberglass screening. The only resonance would be on 30M. Feed is intended to be 450-ohm window line, which will exit between the bottom two louver slats, and wind its way on the outside of vinyl soffit and along vinyl sidings, with stand-offs to the ground floor shack. Run of 75′ or less anticipated. Will use an MFJ-974HB tuner, w built-in 1:1 current balun. No coax intended to the tuner.

Comments about what else might be needed, and what kind of multi-band performance might be anticipated will be appreciated. I AM a bit unclear as to if and why I might need a balun outside of the tuner. Thanks, and also for the useful site and discussions.

• The balun in the tuner should do fine.
I donno about the performance, as I have no experience with a rectangular loop. In general, (1) it probably will not tune below its fundamental resonant frequency (10MHz), and (2) attic antennas tend to pick up noise from electronics in house, and put RFI in things. Prolly gonna need some toroids on various stuff.
A 20-6 meter design that would fit in your attic would be an MFJ Cobweb (~9′ square); or, for 80 & 40 a loaded and trapped dipole, diagonally under rafters. Or maybe a fan dipole, with loaded 80 meter wire, and 40-10 full-length wires. Just some ideas.
73, –kv5r

• I’ve had a 160 meter ladder line fed dipole for years. The only thing that ever took it down was me trying to stretch it too tight. On that much wire gravity does cause a bit of droop. I run it so I can get in my driveway and around the house without regard for direction. One leg even runs through trees. You do what you have to do. I have a MFJ 989 tuner and it works all bands fine. When setting your band points turn your power down to minimum note the reading so you can easily return at least close. Slowly add power and adjust as necessary. I do not have an amp so I don’t know what may occur over 100 watts. Feed point is on a tower about 30 feet up. Best antenna Ive had and virtually invisible. HOAs may not even notice.

35. Great article. Question though. I’m getting ready to put up a sky wire loop for 80 meters on up. Searching the internet gives all kinds of answers to what type of balun to use. Some say 1:1 others say 4:1. About the only definitive thing I can find is to use a current balun and not a voltage balun. I also can’t seem to find what length of ladder line to use. I have a 50’ piece of 450 ohm ladder line to work with. I plan to run the LL to the balun mounted outside and then a run of coax to a Mfj 939 tuner.
What would your suggestion be for the balun type and LL length?

• Howdy Kenneth,
For length recommendations, please see the remaining pages of the article, particularly ladder line page 3.

For the balun, a 1:1 current choke/balun, designed for a wide impedance range, such as the Balun Designs 1171. Various RF engineers are now recommending against using 4:1 baluns on LL-fed non-resonant antennas, because (1) at some frequencies where the shack-end of the line is low, and a 4:1 makes it 4x lower (sometimes way too low); and (2) 4:1 baluns lose common-mode choking ability when operating in mismatched conditions.

73, –kv5r

• Hello Harold, Thanks for the very informative article on Ladder Line. I was planning to install a dipole using window line for operation in the 40m to 10m bands. I have a Johnson Viking Matchbox Tuner model 250-23 which is designed for balanced feed line. Will I still need a 1:1 current choke/balun using this tuner?
Thank You,
Alan Young N2BVX

• Probably not, unless you have a LOT of common-mode current to choke off. I don’t know the choking impedance of the Matchbox, but minimize your common-mode current by making the dipole symmetrical, and bring feed-line away perpendicular to the dipole as far as possible. Might want to ask some gurus who have used the Matchbox, in eham & qrz forums.
73, –kv5r

• Thanks for your prompt reply and advise. Will check in with the gurus in eham & QRZ forums.
73, -N2BVX

• Kenneth, Your tuner has a balun built in I think. Mine works fine without an additional balun. Be sure to install the short jumper wire as directed in the tuner instructions it’s only about an inch long and goes to the tuner feed point for a random wire length I think. If you don’t put that jumper in it will bite you literally. I’ve seen some healthy rf burns from just 100 watts. Fortunately I read the directions first. Unusual I know but in this case worth it.

36. I have a fan dipole for 160,75,40 meters cut to length on each leg to have low S.W.R`s it is fed with 85 or so feet of LMR-400 coax.Can I feed it with ladder line and get rid of coax cable or should I build A new dipole for 160,75,40 meters and feed it with ladder line I have manual tuners and auto tuners too.Let me know what to do with the dipoles is the fan dipole as good as the single wire dipole fed with ladder line. I been reading articles on coax and ladder line I get confused on what I am reading I need help on what to do the bands I talk on it is 160,75, and a little bit on 40 meters thanks I need help on what to do. Paul Wozniak…kb9vwd

• Howdy Paul,
No, if your 3-band fan dipole is giving you low SWRs where you like to talk, there’s no reason to go to ladder line.

The only reason to use ladder line is when you wanna run several bands on one dipole and the SWR is very high. But on resonant dipoles coax is fine, and easier to use.

As for putting ladder line on a fan dipole, I don’t think that would work. Multi-band resonant fan dipoles select the right dipole by being close to the impedance of coax at each dipole’s resonance (low impedance point).

73, –kv5r

37. Hi, I am just installing a sky loop with a fundamental of 1.775 MHz. Running 6″ ladder into a high power 1 : 1 for 160 – 10, then 4 ft coax to a DU3000T. The height is 60 ft using 4 tree supports and my tower. My question is ,, my tower is 45 mtr, , what do you think of running the tower legs to 120 ft,,, one tower leg is 250 ft the other is 130 ft. The remainders will run at 60ft. This will give me two legs sloping to 120 ft… What do you think about the horizontal and vertical patterns,and impedance matching?
I could just run the whole thing at 60 ft, what is your “take” on the above.
Kindest regards
Carl. – G4VFU

• Greetings Carl,
A 160 meter sloping loop… I donno, but my guess would be that it will favor the direction of the high side a bit, particularly on 80 meters, since that high side will be a half-wave high (on 80), where it’ll have a lower elevation angle. It will also have slightly lower ground losses on 160.
To see the patterns it might produce (on all bands) you need to model it in EZNEC or MMANA-GAL (the latter being freeware).
The impedance doesn’t matter, as it’ll be all over the place and corrected at the tuner. But do consider balance.
If you run it sloping, best to feed it in the middle of the low side, so its halves will be balanced with respect to ground, and thus keep your feed-line balanced. If you can’t feed it there, probably better to run it level at 60 feet, so it’ll be balanced at any feed-point.
Either way, that’s gonna be a great antenna!
73, –kv5r

• Thanks for the quick reply !!!
Yes it is fed in the middle of the low point. I have just rx’ed my ballon as I have just finished the ladder line, great timing, it came from VK. Tunes up on all bands apart from 28, so I will trim and try for that. I think that may be just asking a bit much. I have just tried out on 20, and works superb, just had a mobile from Italy who was at the noise level, but gave me 5 by 5.
Midnight here in Thailand, so I’ll wait a tad and try on 40, the band opens at about 1 am
Thank you for your take on the antenna,, it was just by chance that I fed in the middle of the low section,, if it turns out as you predict , by chance again that is my preferred direction of north west, Europe and USA.
Once again kindest regards
Carl – G4VFU

38. Getting close to installing a doublet at home. I have an ash tree in one end of my backyard, no trees at the end where the basement shack is (near water supply for grounding, etc.). So it looks like I have two options: basement window entry VERY close to where the feedline [14awg, 4″ spreaders] comes down, and then across the basement to my shack. Straight shot, except that I have a drop ceiling that uses metal framing to hold up the [some kind of wood fiber] ceiling panels. I’d like to stay above that ceiling. It’d cross 14 of those, spaced every 2′ or so. They’d be maybe 3 inches below the LL, all exactly perpendicular to the run of LL. Is it even safe to run the ladder line like that, attached to joists above a drop ceiling? Option 2: just run the LL outside the house, all the way to the shack and in through a basement window there. I have a gut feeling this would be better, though a lot more work. I’m thinking about fashioning some kind of standoffs that I could attach to window frames on 2nd floor, keeping the LL away from aluminum siding. Then the LL would drop down to the entry point. Either way, I live in an area that gets a fair amount of snow. Will I need to be sure I don’t get drifting around the LL at the entry point?

• Hmmm, interesting problem. I wouldn’t run 4″ line 3″ from that ceiling grid. But what you can do is reduce the width of the LL to one-inch, or even half-inch, window line right after you come in and run that above the ceiling. The narrower line will have a much smaller magnetic field, assuming the antenna is pretty well balanced. Remember the 3x rule — 4″ line needs to be at least 12″ away from metal, but 1″ line only 3″ away.

Or maybe drill pairs of small holes, spaced an inch or so, through all the joists and get the wires a few inches higher. Lessee… 14 ceiling grids is 28 feet, 29 joists, or 21 joists on 16″ centers.. Lotsa holes! and you’d need a right-angle drill.. Naaa, too much work!

Another (perhaps better) option is to run twin coaxes from the ladder line entrance point, 3″ above the ceiling grid, and to the balun in or near the tuner. You connect the coaxes’ centers to the ladder line, tie the shields together at both ends, but ground the shields at the tuner end only (so the shields can’t flow any current and radiate). Run them right together, taped every couple feet.

Considering your snow drifts, you might even run the twin coaxes out and up several feet.

Another thing to consider is imbalance and/or common-mode currents could put a lot of RF in your shack, running 28 feet across your basement ceiling. Might need to put a 1:1 choke balun at the entrance point, if needed.

Wouldn’t it be great if someone made shielded twisted pair (STP) cable with 10kV Teflon insulation? 🙂

I hope that gives you a few ideas. Please let us know how it works out!
73, –kv5r

• Well, I went with routing it to the shack’s window instead, which means LL only travels a few feet (7-8′?) from window to tuner balun and tuner. I have a 130′ dipole inv V up maybe 23′ tops, with last 23′ of each leg laying on the top rail of a privacy fence, bent at close to 90 deg to get it to fit. BUT, it tunes! With 110′, it tunes on 80m thru 15m. I might have to adjust it a bit to get 12m and 10m to behave. I put a piece of PVC cardboard in the window temporarily to get the wire through, just so I could test it before putting in a more permanent solution. Despite all of these less-than-optimal parameters, by golly I’ve got a very strong signal getting out. I could not be happier. This is amazing stuff, I’m a believer! Thanks for your help.

• Sounds great! Glad it’s working for you.
If you wanna make it even better, a few things come to mind.
1. Get the apex higher. I’m assuming your apex is the roof; you could put a tripod on the roof and a 22′ mast (galvanized chain-link top-rail is 1-3/8″ and a lot cheaper than TV antenna mast pipe). That would considerably expand your NVIS (low-band) coverage, reduce RF in the house, reduce ground loss, and leave less wire bent on the fence. Put a long SS eye-bolt thru top of pipe, and use some #36 nylon string (or 1/8th” UV-Dacron) to pull up the feed-point.
2. Put mast pipes in 2 corners of your fence and get those points up 22′, if possible. Eye-bolts and string to floating dog-bone insulators a couple feet out from pipe. The bent ends can then be pulled to far corners of fence, sloping downward.
3. Put balun outside the window; it won’t hurt to run 8 feet of coax (use RG-213 if running high power) to your tuner. Use a bulkhead fitting (double SO-239) where it comes in, you’ll love being able to disconnect it right there for storms.
As for getting 12 and 10 to tune, remember those are 9 & 8 foot quarter-waves, so you don’t need much change in length (2-4 feet) to make a big change in impedance at the tuner. What I did was make 3 coax jumpers, 2, 4, and 6 feet, then used the one that moved the wacky point above 29 MHz, which was at 28.4, right where it didn’t need to be.
Again, just more ideas!
73, –kv5r

39. John Dennison, KW4OI
500’ open loop 40’ tall. Plan to use LL feed point at a corner closest to the building. LL to drop straight down to 4×4 post with it’s own ground rod and spark plug lightning arrestor. Post ground rod connected to service and several additional rods around building. LL continues backup at a 45 degree angle to 2nd floor eve, outside 1:1 current balun, 12 foot RG8 to IT-100 tuner RG8 jumper to ICOM 7300.
What can be done to help this plan?

• Howdy John,
Not sure what you mean by “open loop”; if you mean a full-wave closed loop, the usual length formula is 1005/f, which at 500′ would place the fundamental current antinode at ~2MHz, with harmonics near 4,8,16,32. If you use 558.3′ of wire, the impedance dips would fall around 1.8, 3.6, 7.2, 14.4, and 28.8.

Of course, those are very rough estimates, as the usual 1005/f factor is only a ballpark, just like the 468 for dipoles, and is dependent upon the actual wire used (insulated has a slightly lower velocity factor), and the antenna’s environment.

For the balun, make sure it’s a “tuner” or “ATU” balun designed for high choking impedance over a wide impedance range.
On the IT-100, I looked up its specs, and the 125 watt and 10:1 max SWR figures seem rather limited, while the the MFJ-939i claims 200 watt and 32:1 max seems more desirable, with both at \$160 on gigaparts.

On your line length, 40′ down + 22′ (45 degrees to a 16′ second story eave), 62′, is too close to 65 (one of the “bad” lengths), which might make 80 meter hard to tune (a quarter-wave line with SWR on it forms an impedance inversion); I’d shoot for a routing that would use ~80 feet of LL, and plan for a few feet of adjustment to fix a band that that is hard to tune.

Should be a great antenna! Please let us know how it all works out!
73, –kv5r

40. Hello KV5R
This is a great site you have made. Found it looking for information on Ladder Line. You have answered many of my questions in regards to making and terminating it in the shack. I have a question in regards to moister getting into the spacers between the feed lines. If water/moister gets into the tubing will it effect the characteristics?

PS: A friend has talked about making soap so I have sent your site.

Regards
Joe VE3VGJ

• Howdy Joe,
I have ~150 feet of 4-inch open line with insulated stranded THHN wire and tube spreaders and I haven’t seen any SWR change wet or dry. So I would say no. (See my 80-meter doublet).
When considering whether to use tubes or solid rods for spreaders, tubes are much lighter, can be attached with cable ties, and ends can be sealed with silicone caulk, if desired (I didn’t seal mine). Solid spreaders (like 1/4-inch fiberglass garden stakes, or {gasp} wooden dowels) are heavy, and would need to be drilled, slid in place, then silicone caulked to keep them in place — lotsa work!
I did wonder if a tube full of water could short the line and blow through the 600V insulation, but I’ve run 1kW in the rain with no problem.
For spreaders I’d recommend the Ladder-Snap product, if you’re gonna use #14 wire, or Zareba/FiShock brand Rib-Tube insulators (made for electrified high-tensile fencing), attached with 11×1/8th-inch T&B Ty-Raps run twice through the tubes.
73, –kv5r

• Thanks for the reply KV5R
Looks like I’ll be make the ladder line as you have. There are a couple of farm co-ops near me that have the fence insulators you mention.

Regards
Joe VE3VGJ

41. Many thanks for all the info. I am planning to put up a 130 foot center fed dipole fed with ladder line of course! I was going to use 600 ohm open ladder line But your article above appears to suggest that 450 ohm ladder line would be better for multiband operation due to lower SWR.

Rob
VA2FB

• Howdy Rob,
No, you won’t see any difference between 450 and 600, except that when window line gets wet you have to touch up your tuner a bit. 450 (which is #18 AWG at 1″, #16@1″ is ~420 and #14@1″ is ~380) is closer to the geometric mean of impedance variations (low (maybe 35) when feeding odd half-waves, and high (maybe 3500-4500) when feeding even half-waves), so let’s say ~350 would be the geometric mean, with SWR (at 350) not going over ~10:1 on the line, either low or high. But if it’s 600 ohm line the low-z SWR may be 12 and the high 9, but it doesn’t matter because ladder line is nearly lossless even at much higher SWR.
What is important is that the line length is adjusted so that the current & voltage anti-nodes (extreme impedances), at the balun & tuner fall between ham bands, not in the ham bands, where they’d be out of range of the tuner, or worse, arc or smoke things.
The “ideal” situation would be if the line length was such that it presented oh say about 500-1500 Z to the tuner in all the HF bands, because T-tuners are most efficient with a moderately high impedance on the antenna side, rising to ~95% at 500, according to G3TXQ’s excellent research); see also W8JI’s many excellent articles on tuners & tuner baluns.
However, in the real world that doesn’t happen, at least not to any particular formula, because of all the variables in the antenna system and its environment, not to mention the way SWR dips are very narrow and plateaus very wide — it’s impossible to to find a single feed line and antenna length that will land low SWR dips in all the HF bands. But with feed line length adjustments it is possible (and necessary) to get the impedance extremes out of the ham bands, so the balun & tuner are happy and efficient.
I hope this this makes sense! 🙂
73, –kv5r

• Many thanks for the info. Looks like I will use 600 ohm ladder line!

And thanks you for the link to G3TXQ’s research on tuners and baluns. I always thought 4:1 baluns were preferred when connecting ladder line to the Antenna Tuner for the all band dipole. But G3TXQ’s research appears to suggest that a 1:1 current balun would be a better choice at least when one is using a T-network type antenna tuner.

It is too bad that he did not do research on the best type of balun for use with a L-network type Antenna Tuner. (L type antenna tuners typically have lower losses than T-network type tuners).

• The 1:1 current choke/balun will be the best for an L-tuner also. From what I’ve recently read, a problem with 4:1 baluns is they lose both common-mode choking and current balancing abilities when badly mismatched (like running ladder line with high SWR). Baluns with a transformation ratio are only operating properly when they are terminated at or near their design impedances. So a 4:1 balun is really a 50:200 balun, not a “anything X 4:anything” balun. A proper use for one would be feeding a resonant folded dipole (200-300 Ohm feed-point) with coax.

The 1:1 bifilar-wound toroidal-core balun performs much better at both balancing differential-mode currents, and choking common-mode current, over a wide impedance range. This has been proven by balun designers with RF engineering degrees and professional VNA equipment.

The reason most hams think a 4:1 balun is needed between ladder line and coax is that they don’t understand what SWR really is, and they don’t understand what “characteristic impedance” means. They think using a 4:1 will match the characteristic impedance of ladder line to that of coax, and thus make an easier job for the tuner. And it will, but only at low SWR!

For example, a “450-Ohm” line is only 450 when it’s terminated into a 450-Ohm load. Any other load, and now it’s not a 450-Ohm feedline, it’s a variable-impedance feedline, i.e., it has standing waves. The voltage and current goes up-n-down, every quarter-wave. That’s what SWR really is — impedance variations along a transmission line. Or more specifically, the ratio of maximum to minimum amplitude of those variations.

So, in the case of the non-resonant ladder-line-fed dipole (or any other high-SWR system), the characteristic impedance of the line is completely meaningless, because it varies along the line. The impedance you actually see at the balun/tuner depends on where you cut the line, and the frequency. And that only becomes important if that point happens to be at or near a voltage or current maximum where either one exceeds the design limits of the tuner or balun.

The typical “tuner balun” (or “ATU balun”) by DX Engineering and Balun Designs consists of 2 large stacked cores bifilar-wound with Teflon wire rated at 7.5-10kV. The core material is chosen to work well over a wide impedance range. I use the Balun Designs 1171 and very happy with it.

Anyway, too long! I’m no expert, but I’ve found a few who are, and I’m finally starting to get my head around it. Wish I had kept a bibliography; I read a great article about all this stuff a few weeks back, now I can’t find it again…

73, kv5r

42. Thanks for this great site. Another convert here. 1:1 balun just finished and open-wire line being constructed today. One question; how far off the ground should I keep the line? Will be using it for portable ops. Might build one for home use later.

• Howdy Mark,
Ladder line separation from conductors (including ground) is usually cited (in the antenna books) as 3-4 line-widths. That assumes the line is terminated in a balanced load (a symmetrical dipole), and both conductors are the same distance from the conductive surface. The magnetic field density around the line diminishes by the inverse cube of the distance, so at 3-4 line-widths, it’s negligible.
For portable operations, I would think you could run the line 1-2 feet above ground, using small traffic cones or fiberglass garden stakes. Of course, that’s a trip hazard, so you might wanna run a yellow ribbon along with it.
Also, run your line perpendicular to the dipole so it’s in the antenna’s phase cancellation null, and you’ll have little or no common mode current induced on the line.
73, –kv5r

• Thanks. So, if I understand you correctly, if the antenna wire is oriented north/south, I’d run the feedline down the mast and then 1-2′ above ground level in either an east or west direction. Have I got that right? The pole I use is roughly 35′, but I’ll likely collapse the top 2 sections, so it’ll be 30′ high at the feedpoint. It’ll be a 66′ inverted V.

• Yes. Running the feed line perpendicular to the antenna isn’t absolutely essential, but it is the optimum way, when possible. Running it parallel under one leg of the antenna allows that leg to induce common mode current in the feed line.

43. You do realize…. even at 50% loss your only loosing 3 DB, 1/2 S Unit on the receive end. You make it sound as if running coax is the greatest of sins. Believe me, people have too look at this from both sides. I will stay with the convenience of Coax. It’s easier to work with and Ladderline offers no magic over performance overall unless you wanna run multiband and gain that extra magical 1/2 S Unit… SMH

• Yes, of course.
Yet, it’s amazing how many many hams spend \$4000 instead of \$1400 on an amplifier, just to get that extra magical 1/2 S-unit. Seems to me like ladder line is by far the cheapest 3dB around.
Oh, and it doesn’t burn up when you push a kW of 40 meters into an 80 meter antenna, where, by the way, the loss in coax (100′ RG-8) is more like 84%, or 8dB, nearly 1-1/2 S-units.
And on receive, 3dB seems quite magical indeed, when you start hearing all those signals that were 3dB below the noise floor.

44. I really enjoyed this article, now I have my doubts about my plans. I’m putting up a g5rv (full size) and it comes with 70′ of rg8x coax sounds like I need to lose the coax.
Charles
Kn4qeh

• Yes. The 102′ G5RV is a good 3/2-wave 20-meter antenna. On other bands the SWR on the coax section is high and lossy. Varney never intended the G5RV to be a multi-band antenna, yet people keep selling them as such.
The 1/2-wave 80-meter doublet with ladder line all the way to a 1:1 bifilar choke/balun in or near the tuner is a much better antenna for 80-10, provided you adjust the ladder line length to avoid the voltage and current anti-nodes (i.e., extreme low or high impedances) at the tuner end, on all bands.
73, –kv5r

45. Hello

I was wondering if you have ever heard of someone using a Comtek 4:1 balun and using 450 ohm ladder line to an OCF antenna and feeding the balun with 50 ohm coax to a tuner.

Do you think that would work..

• I’m not a fan of OCF antennas because they are unbalanced. Feeding one with LL will make the LL part of the antenna (it will radiate because its load isn’t balanced), unless you put a choke/balun at the feed-point.
The only purpose of feeding a dipole off-center is to find favorable low-SWR points on several bands, where it can be fed with coax and a choke/balun at the feed-point.
IMO, you’re always better off running a balanced (center-fed) dipole and ladder line all the way to a common-mode choke at or very near your tuner. That is much more efficient than feeding an unbalanced antenna then wasting power in a device to force current balance on the feed-line.
73, –KV5R

46. I am looking to put up a 160 meter horz. loop about 50 feet of the ground can I feed it from a conrner , I would like to feed it with ladder line to my house then about 20 feet of lmr 400 to a mfj 989d tunner, I have a icom 7300 radio.

• Yes, and that will be a great antenna!
Talk to Balun Designs about the best one to use for it, probably an 1171.
Make open-wire ladder line if you want to eliminate the SWR variations of wet window line.

• Thank you for your reply I will contact balun design. you are the first one to offer me with help.
once again thanks
NJ1G Carroll

47. Excellent article, easy to understand. My question is, would I be OK running 50 feet or so of ladder line right along the outside masonry veneer, with no gaps between the line and wall surface?. Or, maybe running it inside a polyethylene pipe (irrigation type), bracketed to masonry wall. Would the LL react to brick/concrete, if left pressed against it for such length? Thank you, and 73.

• It might be OK against brick, if the brick stays dry. Running it in poly pipe will add significant dielectric loss. Anything denser than air within 3 line-widths will add some loss.
Suspending it under a soffit, or out from the brick, with 4″ eye-screws would be better.
73 –kv5r

48. I’ve read the article several times. Perhaps you could help me. I am planning a horizontal loop cut for 80 (perhaps 40, but I should have room at an odd shape 80). I intend to feed this with 450 ohm window line. I understand that even if I run the ladder feed all the way into the shack, I should still use a high quality 1:1 balun, like the dx engineering linked, and run short coax to the tuner.

Here is my confusion. If I run the ladder line directly to the balanced input on the tuner, it has an internal 4:1 balun. If I run the 1:1 in advance of the tuner, I’m running coax directly to the SO-239 that does not connect to the 4:1 internal balun of the tuner. My preference would be to connect a balun outside the shack and connect the window line. Then a short coax into the shack. That seems as you describe, but I’m unsure if I need a 4:1 or 1:1 balun. I think my takeaway from the multi read of your great write up, is I will need the high quality 1:1. I will likely never use more than 100w, as I historically never have and lack the capability.

I’m really seeing the benefits of balanced feedline, and look forward to my loop. I’m glad I’ve found information such as yours, and continued to read before purchasing the necessary parts.

Thanks!

• I would (and do) use an external 1:1 choke/balun that’s made for wide impedance range, such as the Balun Designs 1171.
Or at barefoot power you can save some \$\$ just get a FT-240-31 and wind 11 bifilar turns on it.
Trim the ladder line, if needed, if you have a band that the tuner won’t tune.
73, –KV5R

• Thanks for the information, and taking the time to reply. I’ve been considering products from Balun Designs already, thanks for the link to the correct design.

I did my area measuring yesterday. I’m putting up enough wire for 80m. Now, I just have to get on a 28′ ladder to put two eye bolts into the house.

73 and thanks again
Nathan

49. Hey Harold,

I have a 10-40m Zerofive Vert Dipole antenna I am getting ready to install for the first time. I purchased 110ft of True LL 600ohm feedline in an effort to not have the feedline resonant for those bands. I intend on terminating the LL right outside my window to my shack to a Balun Designs 4114T. From there, I will run LMR600 coax from the Balun, in the window to my radio. The coax is 12ft. My question is this: What is the true length of my feedline from a resonance perspective. Is it just the Ladderline (110ft) or LL plus coax (122ft)?
Thanks, John – KM4JON

• Since the balun should provide a high-impedance choke to common-mode, length should be for the LL only. But in terms of impedance transformation it will be the total length, + whatever the transformation, if any, of the balun.
Your lengths sound fine fine to me, just might have to trim a little (~1-4 feet) if it gets wacky in 10 meters.
73, –KV5R

50. Thanks so much for answering so many of my questions that I just couldn’t find definitive answers to. So I can make a Doublet and use ladder line as the feed line and run the ladder line directly into my elecraft kx3, (built in tuner) via banana plug and I should be in business. I hope and think I’m correct in this? Thanks……..Brock KC4SMI

• Well, maybe. You’ll need a 1:1 current balun/choke, and the range of radios’ internal auto-tuners are usually too limited to run ladder-line on all bands. At least, that’s what I’ve heard. Feel free to try it, and if the internal tuner doesn’t get you there, look at a MFJ-993 auto-tuner, which has a very wide impedance range (to 3200 ohms). That’s what I use when barefoot.
73, –KV5R

51. Thank you very much for the many options. I can not put up the Spider antenna, we sometimes get wind gusts up to 70 mph. I will for sure be taking your advice.

Thank You Again
Bill…..KA6SPQ

52. Sir:
I am planning to make a 20/40 meter trap dipole.
How well it work with 450 ohm ladder line?? I am in a bit of a small
place here, Quite a step down from my 4 element 5 bad quad at 85 feet. Any info you can provide will be helpful. I am limited to a lot 100 feet by 30 feet. It will be about 20 to 25 feet up, all I can do.

• Howdy Bill,
I don’t know if LL would work with a trap dipole or not, but with LL you need a tuner anyway, so you wouldn’t need the traps for matching on the shorter band.
In your situation, I’d put 40 and 20 meter dipoles as a fan, or better, crossed at 90 degrees, and run ’em both on one coax. Trim each one to resonance.
That style of 2-band is usually inverted vees, with a center mast and the two crossed dipoles guying the mast. Like the Army AS-2259/GR. And there’s no reason you couldn’t add more dipoles to it, for 17, 15, and 10, though the tuning will get tricky.
Another one to look at is the Cobweb antenna — 20-6 in an 8.5-foot square you can mount on a TV mast.
BTW, if you have an 88-foot span, you could put up what Cebik called the Broadside Doublet, which is just an 88-foot dipole with ladder line (and 1:1 choke balun & tuner). Not gonna be a great performer on 80, but will work, and has the advantage of having a 2-lobed broadside pattern on several bands. Put up as an inverted vee so the end-nulls won’t be too deep.
73, –kv5r

53. Thanks For The Great Info,
I’m a new ham to HF and am in the process of putting up a 80 meter skywire (275′) fed with 80′ of ladder line directly to a MFJ-993B tuner.
What are your thoughts and suggestions on this set up?
Also, what would result from running 12 stranded wire from the feed point of the antenna to the tuner and just route the two wires on seperate paths to the tuner? Sorta like a really wide spaced ladder line.

• Your 80 meter loop with 80′ of LL to a 993 should work very well.
But no, don’t route the feed-line as described. That would make the feed-line a radiating part of the antenna. To be a feed-line (non-radiating) the two wires need to be parallel and within a few inches of each other to provide opposing phase cancellation. Just use some kind of 2-4″ plastic spreaders between the wires. Look up “Ladder Snap,” or Zareba Ribbed Tube Insulators (attach with long, thin cable ties run twice through the middle).
73, –KV5R

• Thanks again for the GREAT and UNDERSTANDABLE info!
Just an update from my last note. I got my “skywire” up and radiating. I ended up with 270′ of insulated 12ga multi-strand, and as mentioned previously, fed with 80′ of window line to the tuner. Height is about 15′ at the feed point, sloping up (ground slops away from feed point) to about 30′ at the highest point. Tunes great on 80 – 20 meters.
I realize I need to get more height, but is there anything more I can do to optimize this system.

54. Using poly pipe provides easy means for clamping. 300 ohm ladder line fits in 3/4 inch poly pipe, Since it is hanging straight down or secured with standoffs, the additional weight is minimum concern. It is much easier to strap ladder pipe run in poly pipe to a walls, span between secure points and even enter the radio shack for connection to a TUNER. Poly has wonderful electrical insulating qualities.

I have my DiPole fed with a 40 ft; vertical drop of 300 ohm ladder line to an Icom AH-4 Tuner at the forty foot mast and then run LMR 195 to the radio shack 120 away. radio. From what you have suggested, it seems I should remove the existing vertical drop of LADDER line (300 ohm) and install a one piece LADDER line from the top of the mast to inside the radio shack and connect to AH-4 that would then be connected to the radio via short coax. Would that give a big improvement? ( I have to span a 25 foot wide driveway from the mast to the radio shack eve and then run down the wall to the radio corner of the building. Would shielding it in 3/4 Poly pipe be okay

Solution: Slide Polypropylene over the Ladder Line. Use DUCT SEAL or Hot Glue to seal the upper end of an inverted “V” dipole or high end of a Sloping line.

Wind now has a 3/4 inch poly pipe; being round, no twisting action occurs. Now the LADDER line stays dry and clean.

Polypipe End caps can installed for weather protection and keep lizards and crawling bugs out. A simple slit cut in the end cap allows the ladder line out and a dab of silicon glue or hot glue seals water intrusion. Lower end of ladder line/poly pipe is NOT sealed, allowing drainage for any condensation etc.

56. I think your statement “Any real current balun will have two cores” is overly broad. A 1:1 current balun only requires one core. An impedance transforming current balun does require two, one for the common mode rejection and a voltage balun for the impedance transformation.

• Thanks, I’ve corrected it to be more specific to 4:1 current baluns, the type with two 1:1’s connected in parallel at the input and series at the output.
My point was that there are so-called 4:1 current baluns being sold using 2 windings on one core, which, according to some RF engineer I read a long time ago, are not actually baluns (they don’t balance the currents).

57. I have read your article as I would like to use ladder line or window line for a folded Skeleton Sleeve 40-20 meter antenna. How ever I was questioning if one could even make the feed out of window line. All articles I have reviewed say to use coax as the feed. Can you advise if you have every tried this or heard of anyone doing same?

• I’m not familiar with that antenna design, but if it’s balanced (symmetrical) you should be able to feed it with balanced line, and a tuner. However, if it has 50-ohm resonances in 40 and 20 meters, probably better to run it with coax and no (or very little) tuner.
The best place for ladder line is feeding non-resonant multi-band doublets where the SWR is all over the place, and coax would be too lossy under such conditions.
I found a picture of it. I would not make an antenna out of window line because if you don’t put twists in it, it’ll oscillate in the wind, and likely soon fail, unless you devise some means of dampening the oscillations.
73, –KV5R

58. OK, I’m sold on ladder line! Problem may be that I live in a mobile home with both metal siding and roofing. My current setup is:

Coax from the antennas (HF, VHF, TV) passes through a 18″ standoff (made from pvc pipe) then down to drip loops before entering a 14″x14″x6″ plastic utility box. Inside the coax connects to bulkhead type arresters mounted in a grounded copper bracket. Coax to the shack connects to the other side of the arresters and turns 90 degrees before entering a short conduit made of 3″ pvc pipe.

My tuner is a Palstar AT2-K.

Looks like I have two options. I’d appreciate your opinion as to the upside/downside factors:

Work with what I’ve got: run 6-8′ of RG-8 to an arrester and balun in the exterior box, then ladder line out is a gentle curve.

Old school: Create a non-metallic panel in the exterior wall and run the ladder line directly through. I could mount a knife switch at the entry point and shunt the antenna to ground when not in use. How large should the non-conductive panel be? 16″x16″ is the most convenient size.

I also live in sheet-metal, and have a plastic junction box outside, with a big PVC thru the wall. But I didn’t try to use it as a ladder line termination point because there’s an AC transformer and some HVAC relays in it.

Work with what you’ve got – the balun and arrestor (well-grounded) in the outside box is much safer, and more RFI-proof.

If you do bring it in, there’s no need to install a non-metallic panel. I once had mine coming right through the metal trailer wall; drilled two 3/8ths” holes & put vinyl tubing for extra HV insulation, pushed wires thru tubings, then caulked & sealed. Another time I came in with short parallel coaxes. Both worked fine but I didn’t like the lightening hazard, and ended up with a balun outside, with 2′ RG213 to a 6″ SO-239 bulkhead fitting (grounded outside) through the wall, above the tuner, where it’s easy to disconnect (no more reaching behind stuff). Then another short coax to the tuner.

So it took me 3 tries but I finally got it to where it’s both safe and convenient. I didn’t realize at first that if you bring it in, then the indoor balun, then ground the coax shield side, then the ground has to go back outside. It’s just better if the balun and any lightening grounds are outside, so when you disconnect for a storm your inside stuff is more isolated from any big arcs.

I wasted money on a 30A DPDT knife switch, then when it came in I saw the connection terminals were like a half-inch apart, way to close to be any good for lightening impulses, so I didn’t use it. They don’t make’em like they used to!

Just my 2 cents, 73!
–KV5R

59. All of these replies have points to look at. I have a tubular tower that is about 41ft high, plan on putting a 80 meter dipole at the top (maybe 130ft on each side) and running ladder line down to the 600 ohm to 50 ohm Balun (bought on ebay years ago, Antenna Products Co, SM-153/N, 2-30mhz 1kw avg 4kw PEP, paid a whopping \$25 for it, someone paid much more than this). This Balun case . will be about 5 feet off the ground, coax from it to a coupler (itself in a fiberglass box), from the coupler 50 ohm to the shack. No open feedline inside the metal building I have. I am hoping to get a good almost all band antenna out of this. Any suggestions from you fellows? I have dipoles up there now, one for 80 and one for 40 but the performance isnt as good as I expected.

• Minimize the length of coax; mount balun on wall just outside of tuner location. Go thru metal wall with bulkhead coax connector (makes a grounding point, plus easy to reach storm disconnect).
Use a 1:1 choke balun designed for multi-band ladder-line doublets, such as the Balun Designs 1171. A 12, 9, or even 4:1 balun is no longer recommended for LL-fed doublets because at some freqs it’ll present very low impedance to T-tuner, where they are very inefficient. Both Balun Designs and DX Engineering sites have tech articles about this; see also G3TXQ article.
Expect to have to adjust LL length a few times to make the system matchable on all bands, so start with several feet of slack in ladder line.
73, –KV5R

60. All great Info… but… I’m new to ladder. Recently put up a G5RV variation. Installed as near to instructions as possible. Yeah, it’s too low..25 ft. Ends at 12 ft or so. 40 ft ladder drop taped 3 places on the max gain systems fiberglass telescoping pole. Horizontal excess 8 ft from ground attached to a long run of pvc. Then into a 1:1 choke. Then 70 ft of a good rg8. Then into A full power Tentec tuner, AL82, and finally a Orion ll. Antenna will demonstrate in excess of 3:1 with the tuner at the low end of 40 and past midway it is totally UN tunable. Supposedly it should be a no tuner antenna. This GS6 ANTENNA IS A NIGHTMARE. TOTALLY FORGOT IT IF IT’S RAINING. I’m sure I’m missing something. Boneheadsoften do.HELP.. arghhhhh.

• The G5RV has never been a “no-tuner” antenna, except on 20 meters, where it’s 3/2-wave. On all bands but 20, the SWR on the coax is very high and therefore very lossy. To fix a G5RV, add wire til it’s about 125-130 feet long, then add ladder line til it reaches a 1:1 choke balun at the shack.

61. This was very helpful, I appreciate it. Probably the best article I’ve seen on the subject. After a long absence I’m getting back into the game with limited antennas due to HOA and considering a multi band attic dipole. My attic is not the most spacious and putting up something like a fan dipole or such, will present many challenges. It sounds like if I can put something up that is at least half wave on 20 (I want to operate 20-10 CW), I should be in good shape if I’m reading this correctly.

• From what I’ve been hearing & reading, attic & eaves antennas are now pretty noisy, due to all the computers & switch-mode power supplies in everything nowadays. Also, they tend to overload wifi devices. Look on Youtube etc for ideas on stealth HOA antennas you can hide outside. Some use a fine wire thru trees, others make 20 meter verticals in fiberglass flagpoles, etc.

62. Designing a budget hidden “antenna farm” consisting of a hidden loop antenna around the eave of an attached garage. Planning to feed it with ladder line connected to a manual tuner inside the house.

Problem: the common wall is a fire wall, consisting of plaster on gypsum “button board” on the house wall, and thick stucco on similar button board pm the garage wall. I’ve researched for a solution online and the only thing found so far would be a 2″ or 4″ metallic sleeve filled with intumescent putty (a type of fireblock material) by Unique Firestop (https://www.uniquefirestop.com/store/products/threaded-firestop-sleeve-system/). These sleeves are metal, but if one was used and ladder line were carefully centered before applying the putty, how much signal would be lost?

My transceiver maximum output is 100 watts. I’ve given up hope of WAS and the Century Club awards; I just want to get back on the air, and do it safely and economically.

If this idea is totally impractical, my option is run a coax from the shack outside the house, then going along the house wall a foot or so, then back into the garage from outside, and purchasing an automatic tuner to connect directly to the antenna.

Our club president was the one who cautioned me that just running the ladder line conduits through the wall without fire protection is a no-no, and online research showed me that the building code has upped the requirements in recent years. I plan to consult with him and other knowledgeable members as part of my planning.

• Have you considered just running a couple small all-thread rods through the wall? Then solder ring lugs on the LL and put between double nuts. Might need to buy or barrow one of these long masonry bits the cable tv guys use.
Or run a short coax outside to a balun. I recently did the latter, used a Balun Designs 1171 but running a kw now.

63. Harold
Can I paint my ladder line with Exterior Latex
Paint to match my vinyl siding.

64. Harold,
I am planning on putting up a horizontal loop antenna mainly for MARS. I have seen a number of loops and designs and am in a bit of a quandary. Most of the designs tell you to install the loop with some sort of ladder line. I am planning on putting up a loop approx. 500′- 540′ long and I have open ladder line that I have already purchased. Would the length of the ladder line make a difference?
I have a Palstar Auto Tuner, can I run the open ladder line to a balun and come in the house with less than 10′ of coax? If so, what type of balun would you recommend? Your comments are appreciated very much!
Thank you,
Joe
W3OYJ

• Hodwy Joe, That should be great antenna!

Yes, the LL length should be around an odd-eighth wave multiple of the loop’s fundamental resonant frequency (see other comments below this one) to place the impedance extremes between bands. Then some trimming might be needed for an upper band to get it within the tuner’s range.

I haven’t used one (yet) but will recommend see: Balun Designs 1171 tuner balun. A coax jumper of 10 feet or so will be fine.

Please let us know how it all works out!
73, KV5R

65. Considering the excessive weight of a high-power 4:1 balun hanging in the air from the antenna wires, our club is considering feeding an OCFD with about 60 ft of 450 ohm ladder line terminated in a 4:1 balun at roof level, connected to 100 ft of 50 ohm coax to the shack. I am hearing mixed opinions about the wisdom of this approach and would appreciate some enlightened advice. A related question: I am advised that an OCFD is in fact a “balanced” antenna because the current and voltage are identical either side of the feed point. I would appreciate confirmation of this technical point in addition to the practical question posed above.
Many thanks
John VA7XB for Surrey ARC VE7SAR

• P.S. This antenna will only be used for 40 and 80 m.

• Hi John,
No, an OCFD is NOT balanced, and unless it has a current balun/choke at the feed-point, the feed-line will be a radiating part of the system.
Running 100 feet of coax from balun to shack will work on 80 but be terribly lossy on 40, assuming the dipole is cut for 80 meters.
To use for both 80 and 40 you will need to center-feed and run ladder line all the way, to a good 1:1 bifilar-wound choke/balun in or near the tuner (few feet of coax jumper is OK). If the doublet is cut for 80 (~130 feet), the impedance will be low on 80 (and a 4:1 would make it WAY too low), and very high on 40, where it’s 1 WL long.
The antenna I run now is a 130-foot center-fed dipole at 40 feet, with ~154 feet (5/8ths-wave @ 3.8MHz @ .95VF) of 4-inch open-wire ladder-line, to a 1:1 bifilar-wound choke in a 989D tuner. It works well on both 80 and 40 at 1kw. I designed it based on engineering documents from both DXE and Balun Designs. They recommend using ladder line length that is odd-eighth-wave multiples, so the line transforms low impedance up to medium (~500 ohms) on the fundamental frequency, and also transforms high impedance down to medium on the even harmonic (ie, 40M on an 80M dipole). Both DXE and Balun Designs are now making 1:1 choke/baluns designed to be efficient over a wide impedance range typically found in “all-band” (non-resonant) ladder-line-fed doublets.
73, –kv5r

• Hi Harold
Thank you for your quick and enlightened reply. I had a feeling that this was not going to work. I was probably hasty in stating that the antenna will only be used on 80 and 40, as it would be nice to have the WARC bands since our only other antenna is a 20-15-10 beam. With that in mind, I think the solution for us is to stick with the OCFD, with a less-heavy 4:1 balun at the 66/33 coax feed point, and with extra attention to adequate suspension of the balun. We had considered using the 10 kw balun from DXE, but now believe the 2 kw version would be OK even at full power and a modest mismatch.
If that doesn’t work, your suggestion of an 80-40 centre fed with ladder line or open wire feeder might be our second option, keeping in mind the odd quarter-wave length for the feed line. We could probably make that work.
It is obvious that an antenna like the centre fed dipole is “balanced” because of its symmetrical geometry, but it leaves me wondering …. if equal voltage and current at the feed point are not relevant, what are the defining factors that make an antenna “balanced”? I am guessing it is a symmetrical current and voltage distribution along each of the legs that is important perhaps??
73, John VA7XB

• Okay, some clarifications:

The classic center-fed 80 (or 160) meter doublet, with ladder line and a tuner, will work all HF bands, though some trimming of the line may be needed to get it within the tuner’s range on one or more upper bands. That has been my experience with both a 160 and an 80.

The line length recommended by DXE and Balun Designs is odd-eighth-wave multiples (1/8, 3/8, 5/8, etc., of the fundamental frequency), NOT odd-quarter. The formula given is 123/f(MHz) x VF x n(odd) = LL length. The general idea is to place impedance extremes between bands, at the tuner end of the line, so that the tuner never “sees” excessive current (like < 25 ohms, or excessive voltage (like > 3,000 ohms).

Not sure where “equal voltage and current at the feed point are not relevant” came from… A “balanced” doublet DOES present an equal and opposite load at the feed-point, thus 180 degree phase cancellation in the feed-line, so it’s a transmission line, not a radiator. Such balance at the feed-point is most easily provided by both geometric and near-field-environment symmetry (same length and height on each end; flat-top or inverted vee, but not a sloper, for example). Simply put, when each leg draws equal and opposite-polarity power, the transmission will not radiate. It has nothing to do with impedance (mis)matching or SWR, just balance and thus phase cancellation.

The idea of the OCFD is to hit a higher impedance feed-point (for parallel feeders), and I hear they “resonate” on all multiples, not just odd multiples (as does the full-wave loop). But the down-side is that the OCFD is highly UN-balanced (at the feed) and thus causes a lot of feed-line radiation, requiring some form of current balun/choke/isolator device at the feed-point. Such devices must handle high current on some bands, high voltage on others, without overheating, saturating, or arcing — so they tend to be beefy and expensive. And keep in mind, the more work a “BAL-UN” has to do, the more power it wastes as heat. Thus, if you use a light-duty balun on an OCFD at high power, you will quickly fry it.

For that reason, I avoid OCFD designs, and also because all the old antenna gurus recommend against their use except for low power.

The long-standing, tried-and-true, recommendation for the multi-band doublet is to center-feed with parallel feeders (window-line or open-wire-line), and use no balun except a common-mode choke (typically a bifilar-wound toroid at the shack end) and a big ol’ antenna tuner.

That arrangement (1) makes a great NVIS antenna on the low bands; (2) works reasonably well at lower angles on the higher bands where it’s > half-wave high; (3) eliminates the problem of coax’ high loss at high SWR; and (4) is simple to design and build.

The down-sides are (1) it requires a tuner and common-mode choke; (2) performance on the upper bands (particularly 10 meters) is rather spotty due to many lobes and nulls in the pattern; and (3) may require tweaking feed-line length to get the shack-end within range of the tuner on all bands.

Sorry for the long reply, but I just did all that research before putting up a new antenna a few weeks ago, so it’s fresh on the brain! 😉

73, –kv5r

• Harold
I am learning so much from this exchange. Thank you for correcting my careless reading of ¼ for 1/8 wavelength. Now … if we were to deploy a 130 ft centre-fed doublet fed by balanced feeder for multi-band use, the new challenge would be the need for a wide range tuner at the shack end. This 1 kw station will be used by a variety of club members having different skill levels and the potential for a fatal mismatch is a significant risk.
Your comments are leading me to think that our simplest solution would be to have separate resonant 40 and 80 dipoles, each with a 1:1 current balun at the feedpoint, fed by coax – not easy, but certainly possible. There would be no WARC band coverage, but that is a lower priority as we primarily use the station for contesting and training purposes.
BTW, years ago I used a “multi-band” 100 ft. long dipole fed with open-wire feeder connected to a 1:1 choke balun fed by coax and an “Ultimate Transmatch” at the shack, but the swr on the coax on some bands was off-scale giving me serious RFI issues.
Harold, thank you for sharing your expertise and time to help us understand and work towards a solution that fits our need. Do you have any objections if we publish this exchange in our club newsletter? I view it as a learning opportunity not only for me but for our members.
73, John VA7XB

66. Harold
I am going to put a Cobra ultra lite in the back yard
on a fiberglass pole. Can I run the ladder line along my
fence witch is PVC without a stand off.

• Hi,
PVC has a pretty high dielectric constant and will probably cause some line loss. You’ll just have to try it and see if it’s enough to matter. For ladder line to work best, it should be surrounded be several inches of air.
73, –kv5r

67. Great info here, thanks!

1 – regarding routing of ladder line away from the feed point @ 90 degrees, is straight down preferred over out and away (sloping) or would it matter so long as balance and symmetry are maintained?

2 – OK to run ladder line inside fiberglass mast to keep it out of the weather or does this affect losses, velocity factor?

3 – OK to splice ladder line to true open wire line?

Thanks -Jim

• Hello Jim,

1. There should be a phase cancellation null perpendicular to the dipole, all the way around it, so I don’t think it matters if the line is vertical, horizontal, or even swagging from vertical to horizontal, as long as it is in that perpendicular plane. And if it’s not, no matter, your balun should choke off most common-mode current. So that perpendicular thing is optimal, but not essential.

2. Running ladder line inside a fiberglass mast will increase losses a little bit, as the fiberglass will put a dielectric in the line’s magnetic field. I have no idea how much it might be; it’ll depend on the thickness, diameter, and length of the mast; frequency; dielectric constant of fiberglass, etc. If you’re considering it just to keep the LL dry, well, consider that the mast will have a lot more surface area than the LL’s web, and encircle the line, so when wet may be worse than wet LL.

3. Yes, you can splice window line to open line. There’ll be an impedance bump from 600 to 400 but I don’t think it will matter.

Please let us know how the fiberglass mast thing works out.

73, –kv5r

68. Harold: Thank you for your input. I was afraid you were going to say what you did (hi..hi..) Based on your response, I think I will leave the system as is.

FYI: There was one more thing I did to eliminate some coax and that is feeding 2 diff wire antennas (a modified fan) with 1 coax line coming down the tower.

HERE IS WHAT I FOUND THAT WORKED for me: [NOTE: My property has 5ft fencing that allows me to place 7 ft high supports for the antenna wires around the property.]

*I made up several Plexiglas plates (5×5″ by 1/4″) and this allows me to mount a ferrite current balun (1:1) on the plate. In addition to the coax line, I also bring the 2 antenna wires (separated by 5″ at the top) down together and they go to the same location at the fence. From this location, I separate the wires (I make a horizontal fan from the center point) so that there is a 5 foot separation at the fence. **I found that I can trim each wire for the band and achieve a flat SWR at the center freq for each band (except 80 & 160M tuner needed). **Note: All the wires that come down to ground are separated at the top by 5″ and at the bottom by 5 feet (at the 7 ft high ground level). >NO WIRES ARE CLOSER THAN 5 FT TO EACH OTHER AT THE FENCE< **All IN-V's are broadside to Europe and the Pacific. So far this system has went through a rough PA winter with little effects to the operation of each band.

40/80 together….60/160 together…..30M works better alone

Thanks again….Bob W3BTX

69. Harold: NEED YOU HELP.

SOME BACKGROUND: I now live in the city (on a small lot) with a 50ft Rohn tower. I have an M2 XR5 beam at the top (around 57ft) and have a long side arm (at 48ft) that sticks out 3ft on each side of the Rohn tower. Both sides of the arms have several pulleys that allows all wire antennas to be pulled up and positioned from ground level. >ALL WIRE ANTS ARE USED AS INVERTED V”S BECAUSE OF JUST 1 SUPPORT (the tower)<

NOTE: I have managed to get all wire antennas (30/40/60/80/160M) resonent and just use an MFJ Mo 998 auto tuner on 80 / 160 to cover the entire bands. *All coax runs down the tower (45-50ft) to an MFJ switch then about 100ft of good coax to the tuner in the shack. I realize there is loss, but surprisingly the system works very well on rcv & transmit with my downsized situation.

MY QUESTION: I am wondering what to expect if I were to replace all the wire antennas (except 160) with a single IN-V using 600 ohm feed line dropping down (3 feet away from the tower) that would connect to a 4:1 5kw balun. Then using a short run of coax to the switch and around 100ft to the tuner. **I picked up an 80meter dipole with 50 foot of 6" feeder from WB2JIX and would use this antenna if YOU THINK it will work as explained. **It's possible to add some feeder line and eliminate all the coax to the house (except for a short run to the tuner) but that would involve a lot more mechanical problems.(More things to go wrong)

Thanks in advance for you thoughts on if this will work?

• Howdy Bob,
In your current situation you have 60-40-30 as resonant antennas with very low losses, and 160 & 80 with moderate SWR-related coax losses on high & low ends of the bands.

If you change to an 80-meter dipole for 80-30 you will have very high SWR on the line on 40 (voltage node feedpoint) and just running ladder line down the tower, then retaining 100 feet of coax, will be bad losses, both in the balun and in the remaining coax. Not worth the change; you’ll be disappointed.

Running ladder line all the way is the only way to (nearly) eliminate those losses, but since you already have 5 resonant antennas, that also isn’t worth the change — unless you just need to reduce sky clutter.

What I would suggest is either:
1) keep what you have, or
2) feed the 160 with ladder line, all the way, to a Balun Designs Model 1171 1:1 ATU balun at the shack, short jumper to tuner. (see http://www.balundesigns.com/model-1171-1-1-atu-current-balun-1-54-mhz-5kw/ ). That one’s made for very wide impedance range (high SWR) found in non-res multiband dipoles with LL.

73, –KV5R

70. Hi Harold, thanks for a very informative article on LL.
I use a 1/2 wavelength doublet on 40 m for portable work. I am currently using 300 ohm TV line and I am looking to replace it with window line.
I use this antenna on all bands from 40 to 10 inc warc bands, with atu, with good success.
I am using approx 10 m of feedline (30′) , is this a good length for this antenna and the intended band usage?
Thanks.

• No. That’s too close to a quarter wave on 7. Go to ~40 feet. That will put your min/max impedance excursions between bands so that in-band the tuner will not see such lows or highs.
73, –kv5r

71. Dear Sir,

Thank you very much for the web page on antennae. I am contacting you because I would like to ask if you kindly could help me with the following. I am a new ham radio hobbyist and trying to build a wire antenna that I will install at my house roof in an inverted vee form. The antenna is called G5RV which is multi band. For tuning this antenna I have an instrument that gives swr vs frequency. I would like to calculate from this results the impedance of the antenna but I am not sure if this is possible nor how to do it. Using Smith Chart?
Appreciate very much if you can comment on this issue and any hints you could tell me.
Thank you very much in advance.
Kind regards,
Jaime Gordon
73 from 4X5JG

• Hi,
The G5RV is a non-resonant design except on 20 meters and its impedance will be all over the place in different bands. You don’t need to worry about its impedance, just build it to Varney’s design and then run it with an antenna tuner.
73, –kv5r

I hope it will not take me too much time to start installation.
I am buying all the components.

Kind regards,
73
4X5JG

72. Can I cross a balanced line of 450 ohm or 600 ohm through an aluminum window, closing it on the wires without risk of unbalance, change of impedance or radiate?

How do I get 2 balanced lines by the same window without interacting?
How to change balanced line easily? Remote switch for Ladder-Line?
I am 100% QRP.

Thanks!

• Yes, you cab cross a metal edge, perpendicularly, with ladder-line without any noticeable effects. Just take care the window frame doesn’t abrade the wire’s insulation.

In effect, there will be a low-impedance “bump” there, but at such a tiny fraction of a quarter-wavelength, it doesn’t matter. The bump may cause reflections and raise the SWR a bit.

The better way is the little board trick, where you make a 1×2 for the window to close on, and go through the board. The board’s edges are wrapped with foam weatherstripping; the window jammed down on it with a pair of parting-stops (little pieces of molding cut to fit between the top of the slider and the top of the window frame), and the gap between the slider and the upper pane sealed with weatherstripping. Not pretty, but a good temp setup for renters, etc.

You can remotely switch ladder-line with a DPDT relay. The regular 10A 240V Omron, with screw terminals, ~\$10-15 from Mouser, should be fine for QRP. At high power, RF-rated relays would be needed (big contact gaps to control arc-over).

73, –kv5r

• Thank you for that answer.

Here I have casement windows. So it’s impossible to use this trick.

Either I use coaxial cable (but I will not be multi-band) or I use a 4: 1 balun at the input and I pass through the window 2 cables (less than 20′). Or that I use 2 baluns 4:1 connect on a coaxial antenna selector to the radio.

On the other hand, I would have liked to maximize my QRP power by using the balanced line as much as possible.

Do you have a detailed plan to remotely control the relays?
Can the relays operate at low voltage and be powered by the balanced line?

I want to install a ”Skyloop” and a ‘Vertical Dipole ”. I think using the line of 600 ohms (maybe 450 ohm – undecided) for the ”Skyloop” and 450 ohm for the vertical of 2 x 20′(or 2 x 22’) allowing to cover from 6m to 20m (40m).

What do you think?

• You can pass through a wood or vinyl window frame, or wall, with 2 small holes, space same as ladder-line; needs a special drillbit (small but extra long). Use 2 brass all-thread rods (10-32), with double-nuts inside and outside. Solder ring-lugs on ladder-line. Seal outside with silicone caulk.

Remote relay — use 12VDC coil DPDT relay, run small wire out to it (#18 zip cord). I doubt there’s a way to use the L-L for relay power as you’d need DC blocking capacitors at the tuner, and at at the loop antenna (else, DC short). And who knows what 4 capacitors would do ti your SWR…

Put relay in a small plastic weatherproof box (PVC, not polyethylene, sun would destroy it); 3 pairs of brass screws (10-32), 1 in 2 out, etc. Run coltrol wire thru a hole and seal all connections with silicone caulk.

Sounds like too much trouble to me. Buy a 6M vertical and put it on the roof, run coax. Put up skyloop, as large and as high as possible, run ladder-line all the way in (as above) to a tuner with internal balun (balanced output).

That would be about as good as you could do, without getting into really expensive stuff like tower and beam, etc.

73, –kv5r

73. I am hanging K1JEK’s Cobra Ultralite ladder line center fed doublet 140′ long. I need your advice as I have at least 3 options to fit into my property limits.

I now have my rope and pulleys up at tree top around 80’ and I have to decide the best way to deal with the ladder-feedline. If I slope the feedline to my house entry point, the 450 ohm feedline length will need to be about 100-110’ which should keep it non-resonant for any HF bands. I can have a 4:1 current balun at the house entry and then it would be about a 20’ coax run to my tuner.
However, I have read that keeping the feedline vertical and perpendicular to the dipole is extremely important for efficiency and avoiding common mode induction. If I slope it to my house then it will not be 90 degrees with respect to the dipole but only 45 degrees making it much closer to one leg of the Ultralite than the opposite end.

So my second option would be to keep the feedline almost completely vertical for the 80’ height and then run it horizontal about another 80’ along the top of a wood post fence with 6” standoffs about 5’ from the ground. The fence is covered with a metal mesh but I figure the 6″ standoffs should be OK?? However this scenario uses about 160′ of ladder and I think this brings me to a ladder line length that becomes a multiple of some of the HF frequencies.

My third option, is to put the balun at the bottom of the 80’ feedline and use about 80’ coax to the house but I figure there will be a lot of coax loss with that long a run at high SWR.

Any advice would be greatly appreciated.

73 Jerry NY2KW

• Hi Jerry,
Well, all that stuff people (including me) write about keeping LL perpendicular is the optimal “do it if you can,” “theoretical best” -type-stuff.

I’d do the first way, your 110′ swagged at 45°. I don’t think you’ll have any problem. If you do get RF in the shack (re-radiating from your coax shield), put a stacked ferrite choke on the coax.

You could also use the 2nd option; I’d go more than 6″ above the fence though; perhaps 12-18″. You could clamp ~18″ PVC pipes to a few fence posts and attach the LL to them.

Definitely don’t do the 3rd option, long run of coax after the balun. Way too lossy.

My first 160M dipole was like: LL down 20′, then ~75′ horizontal, parallel to, 20′ under, one leg of the dipole, last 15′ was direct-connected RG-8 (no balun), and it worked fine (at 100W; might not work at 1500 w/o a coax choke).

Let us know how it works out for you!

73, –kv5r

• Thanks, that’s reassuring. With option one- I guess the ladder will “drape” down and I could get a lot of it hanging down almost vertical before it bends towards the house. With my k1jek doublet type of dipole is there any minimum length of ladder that should be hanging down vertical?

• The elevation angle (V-H) of the feed-line doesn’t matter (for horizontal dipoles). All that matters is that as much as possible be perpendicular to the dipole. Whether your slack is pulled straight down (V), straight out (H), or any angle between, even gently swagged from V to H, looking at it from the top (polar view), perpendicular is best — but it’s still gonna work fine if it ain’t.

Non-perpendicularity (if that’s a word) in the near magnetic field of the dipole, will induce some common-mode current on the line, but since the line is un-grounded this common-mode just bounces back and forth, unbalancing the currents on the dipole halves. Why?

Imagine an instantaneous moment when the opposite dipole halves are emitting North and South magnetic fields, well, you can see they will cancel, so there will be a “null” along the line perpendicular to the dipole. And as we move forward in time, all along the sine wave, the 2 fields are always 180° out of phase, so there’s always that null along the perpendicular line — a good place for a feed-line to be. How far?

If I remember correctly, the RF field decreases by the the inverse square of the distance — but the magnetic field (the so-called near-field) decreases by the the inverse CUBE of the distance — i.e., that sucker falls off really fast! Like, in 20-30 feet you can forget about it (well, unless you’re running some kW).

I suggest that all hams should have to study some basic AC theory, like electromagnetic induction, then stuff like antennas, feed-lines, and coils get a whole lot easier to understand. Well, the math is a nightmare, but the principles are easy to visualize.

73, –kv5r

74. Can a dipole be somewhat asymmetrically? that is,

I have enough run for a ~70 foot dipole/double (?) but wish to cover 80 m band to 10m, which from a seller, offers 125 foot dipole with 50 feet of ladder line feed. Can i form another leg of dipole as an “L” shape? so when view from above it would apper as “L”?

• Yes you can bend the ends of a dipole, either horizontally, or ends hanging down vertically. It would be best to bend both ends the same angle and length, to keep the load balanced. If you put all the excess on one end it’ll be unbalanced load and the ladder-line will radiate.

75. I have to run the ladder line from the back yard, along the house to the shack. I also have a couple of other coax fed antennas back there as well. Is it ok to run the ladder line next to the coax (even zip tied together)?

• No. Ladder-line is surrounded my an RF magnetic field (out to a few inches) and must be kept (a few inches) away from all conductive materials. The minimum separation is typically 4 times the line width.

76. Thank you for a great web site, its very helpfull to new hams like me. I’m building a 80-10 meter doublet ant. 60′ high, 135′ long, using 12 gauge insulated copper stranded, one cont.wire with the “true ladder line” 1 3/4″ between wires, plastic spreaders, 450 ohms to a 1:1 balun, to 55′ of LMR-400 coax down to the MFJ-941E tuner & radio. In my research I am unclear on how long (or short) the matching section of ladder line must be. The distance from the center fed ant. insulator to the balun on the roof is 35′ give or take, too much longer and it will be laying on the roof etc. Again I’m not sure about the VF, maybe 90? Or the length. Thanks for the help! Gary KD2IBQ

• Well I’d just run the ladder line all the way to the tuner. That 55′ of coax is gonna be very lossy on bands where the swr is high.

• I wish I could, but the LMR 400 coax would go through a steel pipe from the attic to the basement which will not work for the ladder line….not able to run it on the outside of the house (landlord) or drill through the walls, floors etc…
no other way to really do it other then to move the whole shack to the 4 1/2′ high, too hot in the summer & too cold in the winter Attic….

Thank you very much. Clarified ALL my doubts and learned a lot.

78. Hello,

I want to put delta loop antenna on the roof of the house. I just can’t decide which is better with leadder line or without ladder line.
Ea antenne 7b delta loop vs m0plk with ladder line?

Thank you very much
best regards
Ales

• Ladder line (and a tuner) is frequency-agile so you don’t have to worry about SWR losses in the feed-line.
If you’re building it and tuning to resonance on one frequency, then coax is fine.

79. Hi, this is a super resource, and thanks for all the q&a. I am a lapsed ham and am now working to get a new license, and also in the process of building a new house, and want to try and make it antenna friendly. The shack willl have to be on the first floor, but in the front of house, and my wife won’t let run ladder line out the front window to the second story roof. I can spec out internal conduit and wiring though. I will have multiple coax lines going to the roof.

I dont suppose it’s a good idea to try and run the ladder in a pvc conduit up inside the house where it would run parallel to the coax I suppose? I can put a remote auto tuner up on the roof though to fed a center fed dipole. Is it possible to configure the dipole with relays to be one of 2 end fed Zepps or the dipole? Would that be useful at all in terms of getting various forms of directionality?

Also, I do have a large tree on the lot, 75 ft or so. I could put a remote tuner at the base of it and run ladder line to to the top and fed an inverted vee. Do you think that’s a better approach than trying to deal with the roof?

Also, what is the best (preferably remote) autotuner that can feed a balanced antenna? I don’t see many that have balanced outputs. I could put a balun on the end to feed the ladder line, but which ones would you recommend for a beginner, both the tuner and balun?

Thanks very much!
Mike

• Hi,
Yes, you could put in a PVC conduit for ladder line but use the 1-1/2 or 2″ thin-wall PVC sewer pipe, not the gray conduit (too much dielectric loss), and be sure it is several inches away from all metal (wiring, ducts, etc.) up through the frame of the house. On the roof you can put two long-radius elbows; don’t glue them; to make an upside-down “J” on top to keep rain out.
But much better would be good coax (9913 or LMR-400) to a remote autotuner, as you say. Putting at the base of a large tree, then a good current balun, then ladder line up to a big dipole, would probably work very well. You’ll need some stand-offs up the tree so plan on a man-lift or bucket truck for that part. Try to make the dipole ~130-260 feet long if possible. In my experience, a large-aperture antenna works very well on the lower bands.
Using relays for multiples: RF relays are quite expensive, and you’re not gonna see significant directivity from a Zepp until it’s like 4+ waves long.
I can’t recommend particular baluns or remote tuners because I haven’t used them. You might look up some of the popular ones then read the user-reviews for each on eham.net, that’s what I’d do.
73, –kv5r

80. Question? I am installing a MFJ998rt to a 4:1 balun to a remotely tuned 80 meter horizontal Loop fed with ladder line from the balun. How can i lightning/static build up protect the tuner from damage???

The tuner is very expensive and i want to protect the station and tuner system????

Suggestions😳

• The 998RT’s manual should cover lightening protection and grounding; if not, contact an MFJ engineer. That’s what I’d recommend.
And you should run coax, not ladder-line, to the tuner.

• How about running 450 ohm ladder line in plastic electrical conduit under the house for a distance of about 50’…..no metal close to conduit. Can that be done? What about running in the same conduit with coax? Any advantage in running part coax to ladder line like a G5RV?

• Don’t.
Ladder line is for open-air suspension — running in plastic conduit underground will have ground induction losses.

• I am running heliax coax to tuner due 130 ft run.

MFJ says it has lightning suppression installed in tuner. I am going to ground it well and add an additional suppressor between tuner and balun.

This should take care of my concerns. Thanks for reply

82. Thanks for your terrific post. After reading it the and the comments, I have altered my design for a 160 meter square loop antenna thusly:

The ladder wire will the feed the loop at one corner via a mast on my roof. The mast is a 10 foot sch80 PVC conduit. The loop is secured directly to the PVC and the ladder wire will drop down the center of the PVC into the shack.

If you see a problem with this please let me know.

83. Hi
Would appreciate your help and thoughts on a problem I have encountered with my Doublet installed yesterday
The Dipole is 130ft long
I have 600ohm ladder line which has been cut to 36ft
my problem is I have an excess of about 16ft of ladder line
which currently sits on top of the roof of my house,Im aware it
needs to be kept away from objects
Will it effect the Antenna if I cut off the 16ft of ladder line
or can I roll up the ladder line
My shack is in a first floor bedroom and have little room for the ladder line to be in free space.
Brian
73s G0 DKZ

• I’ve used LL for years and found that a “heap” or haphazardly spread out excess LL won’t cause a problem. If you coil it up tightly, it does, it acts as a bit of a choke.

84. I use a 130′ doublet in an inverted V configuration Center is 57′ high. It’s 12 gauge wire and I’m using 450 Ohm ladder line (the heavy duty stuff). The ladder line is 173 feet long which goes to a 4:1 balun mounted on the outside wall of my shack, then a 3′ coax jumper through the wall to my tuner. Anyway, I have noticed that this antenna tunes well (flat) across the 160 band. Any thoughts about working 160 with this antenna? I’m thinking the long run on ladder line is acting as part of the antenna. Are there any problems that could occur by transmitting down there.

• The ladder line isn’t acting as part of the antenna if the dipole is balanced (center-fed).
If your 80m dipole will tune on 160, it will work ok but the efficiency will be quite a bit lower than a half-wave dipole (~260′). Your balun and tuner will also soak up a good bit of power with that much mismatch on the output.

85. 20 years ago,before I went QRT, I was a member of MARS, and they recommended a balanced doublet for general use. One of the comments about ladder line was that the way to keep the feedline from radiating was to ensure that the two legs had the same current. Someone designed a tuner with the balun on the INPUT and a method to individually adjust the impedance of each leg using two roller inductors, and two RF ammeters to fine-tune the adjustment.

With that in mind, I was thinking about feeding two automatic tuners with a balun, with the “single wire” output of each one feeding the ladder line. Any difference in impedance between the two legs would be automatically adjusted. I think.

Thoughts?

Tim, N7LRU

• I don’t think it’d gain you anything. The autotuner is a reversible L-tuner, with losses under 5%. The manual balanced-line tuner with 2 roller inductors may be a tiny bit better, but at a whopping cost.

• The problem we’re trying to solve is that at many frequencies outside of the ham bands (MARS, CAP, etc.) the balun feeding the transmission line becomes saturated (right word?) and overheats. I’ve had one melt and short, using only 150 watts. If you put the balun on the INPUT side of the tuner, it never sees a high SWR and, as you have said, open-wire feedline doesn’t care. What I said about balancing the phase was just to keep the feedline from radiating (to minimize RFI). Using a pair of autotuners was my idea, because I’m lazy HI HI.

• My MFJ-993 autotuner uses an internal current balun (2-core) and tunes a ladder-line fed dipole to any frequency from 1.8-30 MHz. At ~120 watts I never noticed any unusual warmth of the case.
Donno why your balun burned up at only 150 watts; suggest you try a better balun, maybe something like a DX Engeneering 2.5k. (I’m no expert on baluns!)
You could perhaps use an outdoor autotuner (SGC) at the feedpoint and just run good coax to it — that works well, tho you do need a pole at the feedpoint to support the tuner.
73, –kv5r

• Balun saturation is a common problem at non-resonant frequencies well outside of the ham bands. The SWR is astronomical, and most baluns can’t handle it, unless you use reduced power with a 2kw-rated balun. If you want to run legal power in that circumstance, the choice is to either buy or build a HUGE balun, erect a second antenna, or build a balanced tuner. A real conundrum. Since I also plan on erecting a large horizontal loop for 160m (ham) and 120m (MARS), the balanced tuner is probably my best bet. Both are relatively close to the ground, to maximize the skywave elevation angle for local message traffic communications (NVIS). With such high SWR, balanced line is the only solution to minimize feedline loss.

I’ve sometimes thought about designing a push-pull linear amplifier with a balanced output, to eliminate the need for a tuner. A pair of 4-400A or 833 tubes from a retired AM Broadcast transmitter would probably work.

86. I have been reading about 600ohm ladder line for quite some time and decided to go with it. I purchased a 160 meter 600oh, fed doublet from True Ladderline. Brian has been very helpful. I was having issues with my tuner, but long story short I ended up cutting the 600ohm
Ladderline down to 60′. I have about 80′ of rg213 coming in from the 4:1 balun/common core choke to the shack. Choke was put inline to keep out ref on 20,17 meter and up freq.
What issues is there or are there using the 80′ of rg213?
I get very good signal reports, better that when i was using a 160/80 meter fan dipole.
Thanks
DJ
VA3KBC

• Only issue is coax loss at high swr. You can bypass tuner and check swr (at very low power) across each band, then use the coax loss calculator to see how much loss the 80′ is causing at each freq and swr.
73, –kv5r

87. Hi there, thank you for publishing all of this great info and actually taking the time to address so many comments and questions (including the negative ones) you are a true Jedi. Anyway, I’m planning to take/pass the general exam in a little under a month so I am trying to plan ahead and get an antenna up that will put me on some of the HF bands I’ve previously not had access to. I’m primarily aiming for 20 and 40 meters and have been recommended by some local elmers to build a G5RV. Due to small residential footprint, I have been considering building the half-size version, but after reading your blog above, I am starting to have some other thoughts.

Let’s say I have enough room to build a dipole of around 50-60 feet end to end. I have already purchased and received 32 feet of 450 ohm ladder line. My tuner is a Diawa CNW419 solid state manual tuner and my radio is an Icom IC-701. Should I just build a dipole (Of whatever length i have room for) and feed that all the way to my tuner with the 450 ohm ladder line or should I go more off of published measurements for the half-size G5RV?

After reading your info on ladder line, I’m starting to believe I shouldn’t use coaxial cable at all if I’m dealing with a center fed dipole and that the dipole length doesn’t matter much as long as it’s at least a half wavelength of the lowest band I intend to use it on. As mentioned previously, that would be around 7mhz which would imply ~66 feet end to end.

Sorry my reply is so long but I look forward to any input.
73. -KG7WPQ

• Yes to the latter point; put up as much wire as you can, feed it all the way with ladder line. That will work better than a half-size G5RV.
If you have the extra supports and can bend the ends to get up ~125 feet of wire (in a Z or C or zig-zag shape) that’ll work 75M OK, too.
73, –kv5r

• As always, I’m finding that the satisfaction of an answered question brings more questions. I’ve calculated the feed point impedance of the theoretical antenna I plan to build as being around 72 ohms, and I am planning to feed that to my tuner with a 450 ohm ladder line that analyzer data from a local elmer has shown to be more like 390 ohms. Should I try to construct some sort of coupling transformer at the antenna feed point to match impedance between the antenna and the feed line? Obviously, feed point impedance is going to vary from one band to the next. My concern is possibly not being able to match to 50 ohms at my ATU. From my previous post, I’m aiming squarely at being able to use this antenna for 20 and 40 meters. I have looked at a schematic for my tuner (Diawa CNW419) and it does not appear to have an internal balun, nor does it have a twin lead connection point. I’m just trying to get a full idea of what I am going to need to accomplish to make this system work without causing damage to my radio.

73. -KG7WPQ

• You don’t need any matching at the feed-point. You will need a good dual-core current balun near the tuner.
I read a few reviews on eham.net on the -419 and they all say it has a very wide range and will tune anything, so you shouldn’t have any problem matching to the radio.
You really don’t need to engineer a non-resonant dipole on ladder-line. Just put up ≥½λ @ lowest freq, run ladder-line to a current balun and tuner — done!
73, –kv5r

88. Hi and thanks for a great blogg site, Harold (Y)

I really got a challenging QTH in Norway and today I use about 140m (459ft) of RG213 from my shack to a corner fed delta loop with a 4:1 balun way up a steep hill side.

Works great as a multi band from 80-10m and the swr is pretty good on all bands!
Because the long length I was thinking of give it a try with a 450ohm LL to get as much power to the antenna as possible to increase my tx.
I use a TS480SAT with Acom 1010.
The one positive thing about having the loop far away from the shack & the surroundings is I got no QRM at all.

What is the best way to do this?
– Go direct to the loops feed point with the LL without a balun?
– Use of balun outside between LL and shack?
– Need about 15 ft of coax between TX and outside connect, OK?
– Is 459 ft of LL usable in length to avoid RF?
– Because of the long length the LL needs to go through some tree tops, resting – is that OK?

73,
Frank
LA4GPA

• Hello Frank!
WOW, 459 feet of coax! Your SWR is low because you are losing most of your power in the coax.

Here’s what I’d do in you case:
Use #10 (2.6mm) stranded insulated wire, make 4″ (10cm) open-wire ladder line. (459 feet of windowed ribbon will be too lossy when wet). Connect directly to loop. Plant poles every 50-75 feet, zig-zag the path as needed to miss trees. Use electric fence insulator tubes as spreaders, every 5-10 feet. Connect shack end to 9:1 current balun, then short coax to tuner.
You’ll be amazed how much more signal you get. Please let us know how it goes!

73, –kv5r

89. I can run the 450 ohm ladder line to the window of my house fine, but at the window I need to connect the 450 ohm latter line to RG 213 coax to run inside of my house to may radio. The length of the RG213 coax will be about 35 feet… To do this, should I use a 4 to 1 balun at the window where the 450 ohm line will connect to the RG213… I then will connect the RG213 to a tuner…. Will all of this work, or should I just do something different… The antenna will be a 130 feet long dipole connected in the center at about 25 to 30 feet high…. I would love to hear your thoughts on this…. Will the RG213 at a length of 35 feet kill the signal or even work at all doing it this way..???? Very best of 73’s… Claude WB4WHH Located in VA.

• Yes, that’ll work, but on the bands with high swr (say, 10:1) your 35 feet of RG213 will lose 17% at 7MHz, 23% at 14, and 31% at 28.5, according to the coax loss calculator. And to go from 450-50 ohm lines you need a 9:1 balun, not 4:1. If you go that route make sure to get a well-engineered dual-core current balun.

• Thank you…!!!!!!!!!…
I sincerely appreciate your answer….. You have an “Excellent” site…. Very best of 73’s….

90. Hi all,

I’m using the G5RV and am very happy with it.
However, why are you all using cheap and rubbish coax with it?
RG8/58/213 are very poor and do have big losses when SWR isn’t 1:1.
I’m using Aircell7 and at the ladder to coax connection I use 1.5m of ferrite clamps.
By doing so the coax can’t radiate and the losses are very low.
Also the velocity factor of Aricell7 and better coax is 83% instead of 66% for RG8/58/213. On top of that, Aircell7 has just 75pF/m compared to well over 105pF for the others.
When comparing these numbers, you notice that this coax is closer to the working of 70~90Ohm coax and as such the losses by bad SWR are far less.
Maybe something to think about, it works for me and many others.
Also last remark, please keep the ladder free of anything and put the G5RV as horizontal as possible for the best results.

BTW Aircell7 is cheaper then 213 and can handle the same power, yet being just 7mm and very easy to bend into small corners.

73’s Bas.

• Who said we are all using cheap rubbish coax? And Aircell is about the same as 9913 and LMR400. And extending the ladder line all the way to indoor auto-tuner is better than them all.
And all modern coaxes are foam PE which is .83-.85 VF, only the OLD you-can’t-find-it 213 is still solid PE .66 — which, BTW, is still great for low-swr feeds, and crap! it’ll hold like 13kv and makes good hv jumpers.
I don’t like Aircell because it tends to collapse internally if you bend it too sharp (whix all foam-pe coaxes will eventually). Actually, #10/2 Romex makes a decent feed if you can lowloss match it 🙂

91. I have 600 ohm open ladder line coming from trueladderline.com. My pole is 35 feet. About 20 feet the ladder line will be next to the pole. When you say double the width of the line away from the pole, is that the diameter of the line or the width of 6 inches meaning 12 inches? I was also told that if you twist the line every 3 feet it would keep it balenced due to being to close to an object. Any help would be appreciated.

thanks n5cwf

• Yes, if your ladder line is 6″ wide it should be kept 12-18″ away from metal tower or pole. If both sides of the open line are same distance from pole, you don’t need to twist it. According to the info on trueladderline.com, the spacing is 3.5″ so I’d go at least 3x that for spacing away from a pole. But ask W7FG, he’s the one with decades of experience with open line!

92. Will ladder line improve the performance of a balanced folded dipole? I’m running a balanced Folded Dipole that see’s 50 ohms from 2-30MHz. I know its lossy as heck and I’m feeding it with approx 40ft of RG58U coax. I’ve wondered if the Ladder Line approach would improve performance for some time.

93. I made a FAN multi-band dipole for 160,75,40 meters what can I feed it with should it be coax or ladder line and if I use coax to feed it do I need a 1:1 balun the tuners I have is Palstar AT5K and a Palstar AUTO Tuner and let me know how long the feed lines should be and should I use coax or ladderline and should the ladder line be 300,450,600 ohms I have a Ameritron linear amp also it is a 1500 watt one it has a 3cx1500a7 my email is kb9vwd@aol.com for more information we can talk about these things.Paul Wozniak kb9vwd

• If you’re only gonna use it on 160,75,40 (and maybe 15) and you trim the dipoles for a pretty low SWR on those bands, you can use coax.
If you also wanna use it on its high SWR (non-resonant) bands (20,17,12,10) you should use ladder line.
If you use coax, you might put a good 1:1 current balun at the feed-point and (for high-power ops) a choke (the kind with ~10 stacked ferrites) on the coax before it comes into the shack, to eat any RF on the outside of the shield. The coax length won’t matter if the SWR on the line is pretty low.
If you use ladder line (450 windowed or 600 open) on the non-resonant bands, use one of the lengths specified later in this article, to reduce the amount of common-mode RF coming down the line into the shack.

73, —kv5r

94. I see this is old not sure if I’ll get a response or not. I have the zs6bkw g5rv and have it up 35 feet or so. The ladder line is 40 so it’s laying on the ground. I see you told someone else to keep it away from the ground. So is there any other way besides a taller tower to remedy this? I haven’t ran the coax yet I have had to order a longer run, which brings me to my next concern… My new home qth I’m basically forced to run from the shack to the opposite side of the house, about 110 foot or more.. I have the coax angled away from the mast.

• Well it’s old but you still might get a response 😉
Ladder line, like any parallel wire with AC on it, has a magnetic field around it. Most of it cancelled out by the opposite phase of the other wire, but not all, because the two wires are not exactly in the same place and their opposite fields are not exactly overlapping.
Now we know that AC magnetic fields induce currents in any nearby conductors — so if your ladder line is layin on the ground, or against some metal, there goes some power wasted into heat.
So that’s the beginning and the end of keeping parallel feeders away from conductive materials. Fortunately the magnetic field decay by the the cube-root of the distance, so it aint very damn much, just a few inches, but those few inches are very importan t and must be protected.

95. Hi,
nice and useful information!
Just a question..
I’d like to mount a NON resonant dipole feeded with 20 meter of ladder line and i think i should buy a tuner.
Should i take a balanced one (Palstar BT1500A) or also a Palstar AT2KD will work fine?
Thank you very much for the time you dedicate in answering to me.
IU1CYF
Paolo.

• Hi Paolo,

I’ve never used a balanced tuner because they are so expensive (2 roller inductors) and not as versatile as a regular tuner. I use an auto-tuner, just push tune button, clickety-click, talk.

They should be bit more efficient, with the balun on the input side, it sees a match on both ends, so operates efficiently in its design parameters.

You should read BT1500A reviews by owners, on eham.net – http://www.eham.net/reviews/detail/4517.

73, —kv5r

96. So I’m a bit confused, from a radio perspective, is there any difference between a ladder line and an otherwise identical twin-feed without the ladder cut outs?

I seem to recall that the very presence of the insulator coating has a major effect on propagation within the wire, so I suspect an “open” ladder with no insulator on the wire between the rungs would be different than the stuff I find online, which is essentially normal twin-feed with rectangles cut out of it. Or is it different? Or is either different?

• Yes, open-wire ladder line is a little bit more efficient than window line. In practice, there’s a lot of difference between coax and any type ladder line, but little difference between window-line and open-line.
Window line gets a bit more lossy when wet, which is when open-line is better.

97. I’m a little new to the hobby , just know enough to be dangerous,, I am thinking about putting up a 5 band 2 element quad but i would have to either run 5 coax lines or run an antenna switch , I don’t want to do either , could I run open line and just tie all the lines together , what do you think ?

• I don’t think it’d work. Multiband elements on one feedline “select” the proper element (for a given frequency) by its feedpoint impedance being closest to the feedline’s impedance, a condition where maximum energy transfer takes place.
Feeding a bunch of loops, whose feedpoints are ~50 ohms, with 450 ohm LL, it won’t “select” the desired driven element, but one closer to 450.
It might work if you just tie all the feedpoints to one 50-ohm coax and run that in. Even then, adjusting all 5 loops to 50j0 in each band will be an endless nightmare, because they interact both with each other and the reflector loops as well. Model it in MMANA first and see!
I think you’d be better off building a spider beam, there’s plenty of plans and kits for those, they’re simpler than a quad, and from what I read they work pretty well.
I’ve never built either one so that’s just IMO.
73, kv5r

• It is similar to the case of a multi-band dipole that uses separate, different length legs all joined at the center. Only the legs tuned for the band in use present a matched impedance and radiate.

The feedpoints for quad loops are actually about 100 ohms *at the frequency it is tuned for*. The other loops will be higher or lower in impedance and thus present a mismatch and not radiate or not radiate much.

In this situation, I have successfully used a 2:1 balun at the point where the loops join and fed it with coax.

The real problem with feeding a quad or any other rotating antenna is keeping the ladder/window line away from the tower as it rotates.

Thus, I’d recommend using ladder/window line up to the bottom or mid-point of the tower and coax the rest of the way. You can make a matching transformer between the window line and coax at that point using window line or some other method.

• Yes all well and good, except he wanted to run multi-quad-loops on a single ladder-line without a switch, and that ain’t gonna fly. It’s not like a ~50-ohm fan dipole on 50 ohm coax.

And while a 1-wl loop is 100 ohms free-space, it’s much lower in the presence of parasitic elements. Just like on a yagi the DE in free-space is ~72 ohms, but with R & D parasitic elements it’s like ~20 ohms. You can’t expect a 450-ohm LL to select the right DE by impedance matching alone, (unless the DE’s are 450 at the feedpoint, maybe a big delta-match might do it), otherwise you’re gonna need a box full of relays up there.

Putting LL across a rotator isn’t hard at all, you just hang a big ol’ loop out there and it’ll spiral 180 degrees either way just fine, if it’s big enough it won’t touch the tower.

73, –kv5r

98. Thank you for an interesting web page, I had been intending to run openwire for the last 30 years but only recently did.
The aerial was cut as a standard halfwave dipole on 40m, initially fed with 80ft of RG58. Changing to openwire with old school seperators made from wooden dowel the 40m results of course did not change much. However running the aerial on 20m where the impedance is very unfriendly was an eye opener! Pretty good on all bands 40m and higher, as you mentioned I also don’t believe in the single core 4:1 current balun, I used two seperate FT240-43 rings each with simple twinflex as a bifilar winding, all driven by a t-match atu. I have since taken this balun apart in favour of a 1:1 current balun. I experimented with different core types and windings, some efforts got pretty hot at high power and did not have very high common mode impedance. The cores I am using are working well for me. I intend to arbitarily lengthen the aerial to avoid resonances, just to defy the masses! Best regards David G0FVT

99. That should read not high enough and no I don’t use the 949e anymore since I have a auto tuner in my Ken wood Ts 570. Balun between ladder and rg8x coax should be removed right? K8BLS

• Well, not necessarily. Every installation is different and if it’s working well with the balun, just leave it. Or remove it and see if it’ll still tune on all bands with your radio’s internal tuner.

You’ll probably see some improvement if you cut off most of that excess RG-8X you have coiled up; that’s gonna be pretty lossy at bands other than 20M. If by “way more” you mean like 30-50 feet, yeah trim that off; if it’s like 10 feet or less, don’t mess with it.

73, –kv5r

100. I like the g5rv I installed in 2001. Your right it never tuned right unless you had a tuner which has a 4.1 balun in it (mfj 949e) so I got the idea to put a 4.1 between the coax and ladder line, guess I should remove it. I have the AT in my Ken wood ts570 so it does fine. The leads from the center touch nothing, but the ladder line lays on the house flat roof tar roofing and the center is hooked to my brick chimney about 35 feet from ground level. I have never been able to get amps to work right but the 100 Watts works good 1.1 swr. I have way more rg8x than needed so just coiled it up. I’ve been told its not night enough and using it as a inverted v is bad, they say flat topping would be better. G5RV 10 thru 80 meters is what I have center feed ladder to rg8x coax cable. Good day. K8BLS 73’s

101. I was thinking of using ladder line to feed a 2 meter/70cm antenna. Is this a bad idea? I can’t seem to find an antenna tuner for these bands.

• It will work for 2 meters but probably not for 70cm. I seem to remember reading somewhere that the line width needs to be under ~1% of the wavelength.
My first 2-meter antenna was a 10-element yagi built from old TV antenna parts. I modeled it (with MMANA) to use a folded dipole driven element and spacing such that the feedpoint was 370 ohms, then fed it with with 1″ #14 LL, which was 370 ohms. On the radio end, I matched it with a simple L-tuner I made, which was 1.5 turns of #12 solid, 1/2″ ID, and about 6″ of RG-58 for the capacitor (designed using some old software I don’t remember). That connected to a couple feet of RG-8X to a little VHF SWR meter. By removing the outer jacket of the RG-58 stub and taping the end of the shield, I could scrunch or stretch the shield and thus adjust the capacitance. It went flat at one point! That antenna worked great and I regularly hit repeaters at 125 miles.
I built that because the local ham guru told me it was impossible to use ladder-line on 2-meters!
73, –kv5r

102. Thank you for this excellent site and blog. I have a full wave 80 m delta loop that is fed with a Q section of RG11 connected to 50 ft of RG8U then into the rig with a 1:1 SWR at 3.8 Mhz. I tried 450 ohm ladder line to an external tuner next to the rig and was getting a lot of RF in the shack. If I use about 20 ft of 2 sections of parallel RG8 center conductor into the tuner should that help in reducing the RF in the room? Also in your opinion how much better percentage wise is ladder line versus a “Q” section in this configuration? I’d like to use the ladder line for multi-band use. 73, Gary W8vi

• Well, as explained in the article, ladder-line has much lower loss (almost none) than coax, at high SWR.

I’ve never tried q-section matching (which is good for 1 freq only); or parallel coax feeders. I think that running your ladder-line to parallel coax feed-line (shields tied together at both ends, grounded at 1 end) should perform like ladder-line but without the RF in the shack problems. Parallel coax feeder does not suffer high loss (at high SWR) like a single coax.

Another thing worth trying is use ladder-line to tuner like you did, but change the length to avoid common-mode resonances on the line, which is the usual cause of RF-in-the-shack problems with ladder-line. Good lengths to use are listed elsewhere in this article.

Many hams just run a short coax to an outdoor balun. However, baluns are also lossy at high SWR, but with ladder-line you’re either using the tuner’s internal balun, or remoting one outdoors away from the shack a bit, so losses will be about the same either way (I think), assuming similar balun design. And in either case, it should be a two-core current balun; the single-core ones are a hoax and are not baluns at all (according to some RF engineering articles I read a while back).

Vy 73, –kv5r

103. what is better using a G5RV with a 450 ohm or 300 ohm ladderline ?
which will have a lower SWR using an
external tuner the 450 ohm or 300 ohm ladderline ?
what is the difference between the Truetalk G5RV 450 ohm antenna and a
G5RV antenna using 300 ohm using a balum at bottom which antenna is better ?

• It’ll work with either 300 or 450. Varney’s original design used 300, but US-made ones use 450 just because of its availability. Either one will need a tuner except perhaps on 20 meters.

You don’t need a balun at the ladderline-to-coax connection, the length of the ladder-line does the impedance transformation to 50 ohms (more-or-less), that’s why it’s a specific length. Of course, people selling them with baluns will say otherwise 😉

A balun is always wasteful and IMO should never be used unless there is some problem that can (and indeed will) be solved by using one.

73, –kv5r

104. Built a parrell dipole that is centered on 3915 and 7200 fed by RG213u coax, my first thought was to run
NR14# LL had about 100′ that was to much LL hang on my roof it moved around some with the winds at this QTH though I better use coax an have. My question is, Do you think thereare shorter leanths of 450 LL
that could be used to get a match both on 75m & 40m with a tuner using 80′ or less feet 450 LL?
Thank You, Walter

• Yes, 80 feet is one of the “good” lengths to use. See page 3 of this article.

105. I am thankful for information such as this. I wanted to note that I attempted to run ladder line along a copper roof cap for about 8 feet. I stood it off from the cap using wooden toilet paper holders that were about 6 inches high. Not a good solution. Running along that length, at that distance, my SWR wouldn’t go any lower than 2.0 on most bands, whereas it was 1.1 to 1.3 without running it that way. I am now fashioning away to avoid the metal as much as possible.

106. Thanks for the blog i found it very useful,just about to use 3oo ohm ribbon for the first time on my 40 meter loop. Having probs getting supported high enough being vertical. many thanks again 73s

Phill

• 300-ohm ribbon, if you mean the TV type, is pretty lossy. It’d be better to use 1″ windowed, or even better, 3-6″ open-type ladder line.
There is a 300-ohm 1/2″ windowed line (hard to find), that would probably be OK. The general rule is, the less plastic dielectric between the wires, the better. A line with a 95-98% velocity factor has so low loss you can forget about SWR-induced line loss.

See also my feedline calculator — for example, for a 100′ line at 14 MHz with a 10:1 SWR, RG-8 will lose 44%; 300-ohm tubular (that oval stuff) is 31%; 450-ohm WLL is 11%; and 600-ohm Open-wire line is 8%. Big difference!

73,
–kv5r

107. whats a good 450ohm line length longer then 86ft , i think my run now is about 120-130 ft… the hard part is the run across the roof from the tower to the shack it whips around alot in that span and i don’t really want to poke more holes in the roof for supports.

I found a nice static drain and lightening/emp protector and find a 9ft coax line works well from the balun to the auto-tuner
please see photo’s on my QRZ.com page.
ko6kL

• Nice setup you have there!

The next non-resonant length would be around 110 feet.

You need to put twists, at ~1 twist per 2 feet, in windowed ladder line to keep it from flapping around. The twisting cancels aerodynamic oscillations. After you put in the twists, all it will do is just swing back and forth a little in the breeze. Mine spanned about 60 feet horizontally without problems.

73,
–kv5r

• Including twists to cancel wind effects sounds like a good idea. But I’m guessing that in cases where the feedline is also part of the antenna (G5RV) twists may degrade. Unsure … ? My G5RV has no intentional twists in the ladderline, and has been awesome over 16 years, 8Band-DXCC, etc.

• The ladder-line part of a G5RV is not a radiator, it’s an impedance transformer, so putting a few twists in it should not be a problem. Indeed, most parallel line is “twisted pair.”
The reason it doesn’t radiate is because it’s terminated in a balanced load (the 102′ center-fed dipole), which causes 180 degree phase cancellation in the feed-line.
73,
–kv5r

108. Ok new guy here …g5rv using a alum military pole on my rv im portable they are saying not to have ladder line up aginst the metal pole but what if said pole is isolated from ground..? Im in the oilfields of southern texas fulltime rver so trying to be more portable than most….jimbo

• It’s doesn’t matter if the pole is grounded or not. If the ladder line is too close to it, the line’s magnetic field will induce RF into the pole, thus turning some of your power into heat. You can make stand-offs pretty easily with 1/2-inch PVC. Make them ~6 inches long; drill a hole thru each end; secure the pvc standoffs to the pole with cable ties (or wire); and secure the ladder line to them with cable ties (or monofilament fishing line).

Hey where in Southern Texas? I grew up in the RGV, near Harlingen.
73,
–kv5r

109. Ladder line at 14 or 16 gauge is a bit pricey when running 100 ft. How about using some spacers and tie wrap to make true (not windowed) ladder line?

• Sure, true ladder line is best, if you don’t mind the work of making it. It will perform a little better than windowed line, particularly when wet, and have lower wind-loading. I’d use #14 insulated stranded THHN wire (or #10 for high-power), and perhaps some 1/4-inch thin-wall UV-stabilized acrylic tubing for the spacers (3-4 inches), notched on each end using a suitable jig on a router table (or similar); pull two wires taut between trees, insert notched spacers every 3-4 feet, and glue ends with silicone caulk or hot-melt.
Of course, any copper wire it way too expensive nowadays. I once made ladder line from #17 aluminum (electric fence) wire, and pieces of plastic clothes-hangers for spacers, and it worked OK for a 50-foot or so run.
73,
–kv5r

110. On a G5RV how close can I come to a 4ft chainlink fence with the latter line? Also can part of the latter line touch the ground? I plan on burying the coax run thru the back yard to the house.

• Keep the ladder line several inches away from fence and ground.

• I also am running a G5RV. Im new so forgive my stupid question. I have about 60′ from the shack to the feed point at the ladder line. Can I feed w ladderline to decrease loss, can the feed line be buried. My plan was to bury RG-213 in pvc to feed it but I wanted to find the lowest loss method.

• The ladder-line on a G5RV is a matching section and its length should not be changed. It provides a fairly low SWR on all HF bands (except 15), so feeding it with coax should not be excessively lossy.
73,
–kv5r

111. Was wondering about the interaction between the ladder line from a G5RV feedpoint to a balun and a 5mm wall aluminum pole that is supporting the G5RV feedpoint. Since I was going to rig up a pulley on the feedpoint pole to lower and raise it in need, what should I do about keeping ladder line away from supporting pole?

73 de ZR1HPC
Hylton

• Hi,
You need to keep the ladder line away from the pole, at least 2x-3x width of the line. You could bring the line away from feedpoint at an angle, or mount your pulley on an angle-bracket to offset the feedpoint about 15-20cm from pole then bring ladder line down parallel to pole. Either way you need to mount the balun to a stand-off bracket of some kind. Be sure to put a few twists in the ladder line so it won’t flop in the wind like a ribbon.
73, –kv5r