Shortwave Antennas

Understanding Shortwave Radio Listening
and Antenna Design and Construction

Copyright © 1999-2012 by Harold Melton KV5R. All Rights Reserved.


Understanding Shortwave Antennas: Page 1

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Introduction

Who needs this article? Anyone who is a new shortwave radio listener. Shortwave listening is a bit more complicated than AM or FM radio listening, and satisfactory results depend upon designing and installing a good antenna.

Why? Shortwave radio signals travel great distances. They bend around the earth by reflecting off the ionosphere.

What’s that? The ionosphere is a finicky mirror! In the daytime, it reflects higher frequencies, and absorbs lower ones. At night, it reflects lower frequencies and passes higher ones. Around sunrise and sunset, the middle frequencies seem to travel best.

Sooooo... Is that daytime at my house, or at the far-away radio station? Good question! Answer: Somewhere in between. It means that higher frequency, daytime bands will bounce into the US from the west in the evening, because it’s still sunny over the Pacific. Likewise, stations from the east will bounce into the US in the early morning hours, increasing in strength through midday, then fading out as the sun goes down over the Atlantic.

This is too complicated! Not at all. You will soon learn to locate your favorite shortwave stations on the right frequency, depending on what time it is. Shortwave broadcasters may use several frequencies, rotating through them every day. When it’s time to change, they make an announcement.

What if I’m not listening when they make the announcement? Part of being an avid shortwave listener is collecting radio schedules. These are found on the Internet. You can also just spin the dial and listen, and keep notes of what is where, when, and make your own custom listening schedule.

Ok, so what else do I need to know to get started? Your little portable shortwave radio has a useless antenna. Oh, it’s fine for FM — but shortwave antennas need to be at least fifty feet long to be useful!

Oh no! I can’t put up some big, ugly antenna! All it takes is a very fine wire. It can run out the window to a tree, or stapled along under the eaves, or even in the attic. Another part of being a shortwave listener is designing and deploying the most clever antenna possible, balancing visibility, reliability, and performance.

Ok! I think I can do that! Sure! Anybody can do it. Millions of people all over the world use shortwave as their primary or only source of information.

So, just what is an antenna? Technically speaking, an antenna is an impedance matching transformer. It matches the low impedance of a transmitter or receiver to the extremely high impedance of the surrounding space. It converts power alternating in a wire into power alternating in free space (or air), and vice-versa.

Do I need to know about impedance matching? No, but if you want the best possible performance from your antenna, you should design it correctly. You need to know how to get enough signal to your radio to increase your listening options, and reduce annoying signal fading. A poor antenna converts very little signal, but a good antenna converts a lot more. Antennas also pick up noise — man-made and natural — and you want your antenna to receive more signal than noise. Also, you will want an antenna that is physically strong, so it will stay up through many years of storms. In most areas, it must also be well hidden.

Why does the antenna need to be so long? Because shortwaves are long (they are called “short” waves because longwaves are thousands of feet long!) If you only want to listen in the daytime, 50 feet of wire is fine. However, if you also want to listen to the lower, night-time frequencies, you’ll need 100 feet or more.

Why? The length of the antenna needs to agree with the length of the longest radio waves that you want to receive. Shortwave broadcasters use frequencies that are from about 50 to about 400 feet long, and an effective antenna needs to be at least one-fourth of that length — and one-half is much better.

I live in a Property Owners’ Association… Many people in the US now live in restricted neighborhoods. These usually have rules (which you agreed to by signing the contract) that prohibit outdoor antennas. They don’t want you messing up the neighborhood by exercising your constitutional rights, so they require you to enter into a contract that restricts your rights. I call it, “Communism by Contract,” for that is exactly what it is. It is also discrimination, because shortwave radio is just another information source, like TV and the Internet.

What to do? I’ll show you how to put up simple, effective shortwave antennas that are almost invisible. If your local communists can’t see it, they can’t object to it, since the rationale for their anti-antenna ruling is one of visual appearance. If they do object, you still have options. You can fight the ruling and get an exemption. You can fight on the grounds of a federal FCC ruling called PRB-1, which covers small satellite dishes, but may, in the spirit of the law, add weight to your argument. Or, you can simply hide your antenna better, such as running it under the eaves or in the attic.

Is this going to be complicated? Not at all. There are standard formulae for various antenna designs, and standard (common-sense) mechanical practices.

Why are there different designs? Again, it depends. You may want your antenna to transmit or receive equally well in all directions, or in one direction only. You may want it permanent, temporary, or hidden.

Oh! You mean, like a CB ground plane versus a TV antenna! Correct; and there are serveral other designs and parameters which we will consider herein.

Like what? Like whether the antenna design has a wide or narrow bandwidth.

Bandwidth?! You just read on!

Continued…

38 thoughts on “Shortwave Antennas
  1. > I call it, “Communism by Contract,” for that is exactly what it is.

    Okay, but Home Owner Associations are peak capitalism. It’s all about individuals (not the Government) wanting to increase the value of their houses (i.e. capital) by making sure their neighbour’s house looks nice.

    HOAs suck. But only because they put profit over your “rights”.

    Otherwise, lots of great information here. Thanks.

    • HOAs do suck, but the premise that without an HOA the neighborhood will go to pot and that they are profit motivated is incorrect. Plenty of areas, in fact, the most lucrative real estate markets in the country have fine homes, are impeccably maintained and have no HOAs…I suspect that in the long run, HOAs actually lower property values due to their inherent ability to attract anti-property rights tyrant personalities to their boards

  2. Under FCC rules the first 12 feet above your roofs ridge line is pretty much a guarantee:

    https://www.fcc.gov/consumers/guides/installing-consumer-owned-antennas-and-satellite-dishes

    After that you have to negotiate and/or get a permit.

    HOAs cannot stop you from putting up a 12-foot (from the roof ridgeline) antenna. I just put up two 10+ foot antennas (before I found it was 12 feet) on my roof over 4 months ago and I live in an HOA and not a word yet. They can’t do anything even if they wanted to.

    • I forgot to add that it does say RADIO antennas are not covered but in practice nobody’s going to use that to fight you. An antenna is an antenna to most people. It is discrimination as you said, in part because there are a lot of blind people in this country who have to settle with radio. A TV antenna or satellite dish is useless to them and they have the same right to get information over the air as a TV watcher.

      Quote from FCC:

      “Antennas used for AM/FM radio, amateur (“ham”) radio, CB radio, digital audio radio services or antennas used as part of a hub to relay signals among multiple locations are not covered by these rules.”

      • Yes, the rule was written to benefit the satellite TV broadcasting industry, not citizens. Follow the money…

  3. I have some 5 element brown ribbon cable made for outdoor use that I was considering to use for making a quarter wave antenna covering all frequencies between 1.7 MHz and 30MHz.

    In my calculations I started off with the extremes and then calculated the length of the middle element being halfway between the extremes. Then the other two I would make in between the short and middle and middle and long ends.

    Is this the proper way to do this?

    I noticed that the shorter lengths are doing much more ‘work’ if you will in carrying many more resonant frequencies than the longer lengths and was wondering if my calculations should not be viewed in terms of regularly spaced lengths but in terms of regularly spaced frequencies to get the lengths of each element.

    Example of my first three calculations:

    Longest element:
    1700 kHz is 176.34850471 meters (578.571209678478 feet – quarter is 144.6428024196195 feet)

    in between element here not calculated yet

    Middle element:
    3.21766562 MHz is 93.17079332000022873 meters (305.678455774279 feet – quarter is 76.41961394356975 feet)

    in between element here not calculated yet

    Shortest element:
    30.0 MHz is 9.99308193 meters (32.78570187008 feet – quarter is 8.19642546752 feet)

    My goal is to have an excellent multi-element long wire antenna that I can attach to a good antenna tuner via an unun and choke.

    I plan to try to hang the entire length from a tree in front of my house then draping diagonally over my roof to a tree in back with an approximate north/south orientation and use an RG6 coax feed line at one end going to the unun/choke and then into my basement.

  4. Dear Sir,
    I have bought Radiodity rf22 shortwave radio 2 days ago. I have got both AM and FM, but I could not get any shortwave radio stations. I request you to suggest ideas so as to listen to as many stations as possible. When I go to terrace in the evening time, I got CRI and AIR two stations, but this morning I have got nothing. Pls help me.

  5. Hi
    I have a 20m (+-) wire as antenna to feed my WIN radio (1500e).
    Because I have a lot of noise on reception I have some questions:
    What cable should I use to connect the wire to radio. A coax from TV (center -> antenna, 50 or 75 ohm)?
    Do I need to connect the outer mesh to earth?
    Is a balance needed? How to make one?
    Many thanks in advance for your help,
    Regards

    • a few things
      1. use a 9:! unun (balun but its unbalanced to unbalanced ) and ground it at the point of the unun. use coax from tha tpoint on.
      place the longwire as far away from noise sorces as you gan
      the balun (unun) will help in matching the input of the reciever and help lower the nosie floor.
      happy slw’ing

  6. Hi, I live in a house with a sheet metal roof. Will the metal roof prevent me from using an attic antenna? I have vinyl siding and the house is two stories. I don’t think I can run a long outside antenna because my property is short and power lines run right in front of my house. What do you suggest?
    Thanks for your articles. I find them very informative.
    Craig

    • I don’t think you’ll get much signal under a metal roof. Maybe run a single long-wire from an end-gable to a rear fence or tree? Even 40-60 feet will do quite well. Make sure the indoor part of your wire is well away from your digital electronics.
      73, –kv5r

  7. Thank you for this website and the helpful information. Was an avid short-wave collector in my teen years. Had over 30 hallicrafters that I ended up selling in college to I feed myself:) retired now and just bought my first hallicrafters of my adult age on Craigslist. For the thrill as this grown man had tears in his eyes as he bought it. Anyway thanks for the website had enormous laughs at your reference to communists as I use that word to describe lots of people I don’t like and I used to be a real estate agent so I’m all over that concept! Just getting back into the hobby looking to take my technician’s license test and I’m sure I’ll be at your website many times thanks again

    • Yeah, all property associations are run by busybody dingbat communists, that’s why I live out in the country on acreage now.
      My first shortwave was a Hallicrafters, about 50 years ago, good ol HCJB Quito! 5 megawatts.. they used to do vertbal tour of their studio, I could almost see it!

  8. I want to use to lengths of 300 ohm flat lead for short wave receive only.
    One length will run north and south, the other east and west. Single down lead to radio.
    My question is:
    Should I twist and solder the far end of each section and then solder the down lead to all four of the remaining ends? OR?
    Solder the far ends of each flat lead together, solder two of the other ends together and the remaining two to the down lead

    • You should use single-conductor wire for the horizontal elements, and the twin-lead as the feed-line.

      If by “single down lead to radio” you mean a single wire as feed-line, that will only give you a T-monopole worked against ground (or nothing). You’d be a lot better off with a regular dipole and some kind of 2-wire feedline.

  9. Apparently ferrite rod is not a good choice for SW since it is never mentioned in association with SW. But I can’t find any details as to why. Any idea?

    • Because at SW frequencies a dipole is of reasonable size, unlike MW (AM Bc) where one would need to be ~500-1000 feet long. Also because magnetic loop antennas (with or without a ferrite rod) bandwidth is way too small to cover ~20MHz of SW; they’d need to be re-tuned for each SW band.

  10. I’ve heard of a broomstick antenna but I am not sure how to connect it to a coax for a pl259 connection (I need pictures ) and I live in an apartment, please help, thanks.

    • Hmmm, that’s a new one for me! A quick search yields:
      The “broomstick” antenna is a helical-wound vertical, about 2 meters high (or as the room allows); basically, a close-wound coil on a stick, with aluminum disc top-hat.

      Several sites say the base connects to a tuner with a single wire, but one says it works better with a counterpoise (1 or more horizontal radial wires 5-15 meters long).

      So you can either just connect a single wire from the base to the center pin of PL-259, or better, run 1 or more counterpoise wires, connected to coax shield.

      My opinion of “compressed” antennas is that they will work, but not nearly as well as a full-sized linear element — large signal aperture will always gather more signal, the same principle as large mirrors in telescopes gather more light.

      If I had to run an indoor apartment antenna for SWL, it would likely be back-to-back helicals, horizontal, center-fed dipole.

      An antenna tuner or SWL “preselector” will considerably improve s/n ratio, particularly on indoor antennas. Also lots of chokes on computer wires.

  11. In Mumbai apartment highrises are all of RCC concrete with dense populations. Apartment sizes are very small (450 to 800 sq ft) with hardly any possibility to put up an antenna. The small apartment size contains EMI causing equipments (FL tubes, ceiling fans, modems, routers, set top boxes, wifi routers, three mobiles charges etc). In such case the signal is very bad. We hardly have radio sets here which would take two antenna terminal wires. Open Windows are the only source of “cleaner” signals in Mumbai.
    What best antenna you suggest in the windows? How to use a SW dipole antenna for a portable radio which has a long whip?

    • For a radio with only a whip (no ext ant jack) you can only alligator-clip a long-wire to the whip. Run it out the window, across to another building, if possible. With shortwave, anything longer than the whip, and outside, is always better.

  12. Terrific ino. Am SWL, also N3FSH, but gave away all ham gear with shift from Ocean Pines, MD, to Arlington, VA.

    That leaves SWL’ing. Am crammed into tiny condo near Potomac, but do have 25 foot drop for vertical, future antenna tuner, plus newly acquired Tecsun PL-600. Radio impresses me but propagation conditions really volatile.

  13. I have minimum space in the attic and that is where my antenna needs to go. Can it be strung in a zigzag pattern using a dipole with 22 feet on one side and 44 feet on the other. If so, how many angles can there be without affecting reception? Would really appreciate any responses.

    RRoth

    • Hi Roger,
      Several issues..
      Zigzagging a bunch of wire in the attic will pick up distant radio signals poorly, but electromagnetic interference (EMI) from household electronics very well.
      Feeding a dipole off-center makes the feed-line act as part of the antenna (unbalanced load), thus it will pick up even more EMI on the feed-line.
      A better solution is to get 50-100 feet of wire outdoors, as far from consumer electronics as possible. But if you can’t, then just try your attic antenna and see if your signal:noise ratio is acceptable or not.
      73,
      –kv5r

  14. I have a lot of noise on my general communications receivers. I decided to test the house for emissions. So I took my portable Tecsun 660 and walked around the house . After checking the usual suspects , I decided to walk outside with my portable radio. At about 30ft. away from the house all was sigh lent, and I could pull in more stations. My conclusion is when I string my longline I will have to use shielded cable out to about 30 ft then at that point I can start my antenna. I will also then be restricted on length, unless I can double back I would be able then to add a lot of length. What say you?

    • Yes, you could run coax out 30 feet, or more if possible, to get your antenna away from emissions in the house. However, coax will not shield properly unless it’s terminated into a balanced load, so make the antenna a center-fed dipole, and don’t run one leg back toward the house. Also note that your big antenna will probably pick up house noises a lot farther than the little antenna on your portable did.
      Other than that, you could also try to locate your noise sources and add clamp-on ferrite chokes to various cables attached to noise sources.

  15. I have power lines outside on the back wall of house. My bedroom faces the power lines. I got a new SW radio and it does pick up some stations but too much static. 1. could I make my antenna go the roof, how much distance from power lines?
    2. I have a old tv cable satellite disk on a tri pod outside on the ground, could I hook my wire to that?
    3. I have an AM antenna with a round loop in a plastic casing, what is the difference between the two? Or is it SW need more length for wire?
    P.S. I am trying to listen to my Favorite show. Midnight in the Desert, ART BELL.

    • Hi,
      Just keep as far from power lines as you can. Yes, it would probably be better to go out the end of the roof (side of the house) and run insulated wire along the peak (if not metal roof). Don’t go out back of house and run across back yard parallel to incoming power line.

      Running to old satellite dish won’t do any good; and small loop antennas are for AM band, not shortwave.

      You’ll hear lots of lightening static this time of year, even on the best antennas.

      You can get Art Bell’s new show on-line and skip all the shortwave static. See artbell.com .

      73, –kv5r

  16. Hello: I wonder if you know why the Passport to World Band Radio, 25th Edition(2009) is no longer published?

    When this publication ceased publishing, and PCs became popular, I packed my Grundig Satellit 800 Shortwave Radio. I live in apartment complexes that do not allow an overhead antenna on the property. I received many stations with the regular antenna. I purchased the shortwave from a company in Columbus, Ohio.

    I am not a skilled shortwave radio owner, and I miss the activity of listening to people throughout the world. Each time I see the Grundig in its box, I get homesick and want to unpack the shortwave and try using it again.

    I am retired, and I am a poor sleeper at 5:18 AM CDT. Do you think there is enough activity for me to use the shortwave radio again? If so, what type of shortwave antennas are available for apartment use?

    Harold McDaniel

    • I don’t know why they ceased publication. I just download the SW schedules from PrimeTimeShortwave.com.

      Apartment antennas.. I’m a firm believer in maximum aperture, so try a fine (#28) wire thumb-tacked to the ceiling from one corner of the apartment to the other. But that’s also sure to pick up lots of noise from electronics. Signal-to-noise ratio is more important than signal power.

      Is SWL still worth the effort? Well, there’s still lots of SW broadcasters, but most of them are also on the internet and/or FTA satellite (G19), nice and clear. I burned out on SW broadcasters many years ago – it’s all propaganda, paranoia, and pseudo-religion nowadays. But there’s still lots of hams, ships, airplanes and stuff to find — and decoding digital signals (PSK, RTTY, WeFax, etc.) with computer soundcard and sundry free software is pretty neat. (See also my Digital Modes article.)

      That Satellit 800 is a great radio, so just fire it up, see what your s/n is like there, and you might find many new ways to enjoy it again.

      73, –kv5r

  17. I have a Grundig SW radio with a telescopic whip and also a terminal for a external antenna. I live in the boondocks here in Florida and the internal whip antenna does not hack it. I am definitely not mechanically inclined and unable to make an antenna on my own. Do you make antennas for my purpose? If so, will pay for the antenna, shipping etc. if not, any suggestions or recommendations where I could purchase one suitable for my needs? My radio has AM, FM, air, SSB. Thanks. Russ Streiber

    • Hi Russ,
      I don’t sell antennas, and those that do get way too much for them, and 99% of the work is putting it up, which you’d still have to do even if you bought one. SW antennas are generally just a hunk of wire strung up to fit the available circumstances, so there’s really no one size fits all for sale anywhere.
      Many articles, including mine, make it look more complex than it really is–we writers like to provide the “optimized” version of everything–but really, you can run 50-100 feet of any ol’ wire from your eave to a tree, or even tack a wire under your eaves, bring it in thru a little hole, solder on a jack, plug it in, and it’ll work great.
      Even a wire run out the window and thrown over the roof will be 100x better than the telescopic whip.
      My current antenna is just 120 feet of #14 wire strung between two trees, about 20-25 feet high and it works well enough that I even decoded digital radio from New Zealand the other night…
      Just get a 100 foot roll of wire and a jack, then figure out the easiest way to string it up. A roll of #36 nylon trot-line string is handy for pulling up antennas thru tree crotches, just tie on a big wrench and give it heave. Then tie on the wire, pull it up, and tie the string off to a nail in the tree trunk.
      If no handy trees, just go from the peak of your roof gable (put a big eye-screw there) to a fence-post or utility pole. If wire doesn’t reach the available support, add nylon string. etc.
      73,
      –kv5r

  18. Your article inspired me to build my first ever dipole for multiband sw listening only. I own a grundig s350dl as my only portable sw radio which has a 500ohm sw antena input for which I picked up exactly 87.5 ft of no 12 stranded and at HRO Burbank bought 3 insulators. My dipole is horizontally mounted on the eaves of a square building with the > making about a 30 degree (vee) pointing east perpendicular to pwr lines about 14 ft away. I’m not sure if my calc is right but I think this legth of 43 ft and 9 inches per pole works on 5.34mhz? about 60m?. the hro guys said the longer the better and that this would be multiband. Is that true?
    It is center fed with 450ohm hd ladder wire. Is this ok? What else can I do?
    Should I shorten it? I hear a very strong imposing tx on many of the fr that I pick up. I would love to learn more about multiband antennas and would love your help if you may correspond with me. Also, have no clue about another radio, (satellit 750?), for better listening esp to South America and France in particular.
    My phone number is 213 880-4053. Thanks for so much wonderful instruction.
    I’m looking to buy a radio and make a great antenna.

    Uver

    • Hi,
      Exact antenna length is not critical unless you’re transmitting on it. Yes, your 87′ will give lots of signal down to 60 or even 80 meters, and up to 10 meters. But it would be better if you could straighten it out and not have a vee angle, if possible.
      Ladder line is very low-loss (compared to coax) but it’s 370-450 ohms and you may need a way to match it to your 50-ohm radio input, like an antenna tuner with a balun in it. But try without it first. You’ll need to mash the end of the ladder together and solder on a jack for your radio, else get an antenna tuner/balun and connect the ladder to the binding posts on it, then connect the tuner to radio with a short coax jumper. Look at MFJ antenna tuners and look for a low-power one, else look at a receiver preselector. Or just buy a balun (again, low-power rating).
      As for radios, I recently got a $25 RTL-SDR dongle and plug it into USB on the computer. Run SDR-Sharp free software; get the little adapter pigtail for connecting your antenna to the dongle. I’m getting 3.5 to 1800 MHz with the Nooelec Mini T2 dongle and the experimental HF driver. It turns your computer into a broadband radio. I added a discone scanner antenna (at 25 feet) for VHF/UHF. Loads of fun!
      73,
      –kv5r

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