tunable, foldable, collapsible dipole for VHF/UHF
© 2002-2011 by Harold Melton, KV5R. All Rights Reserved.
This handy and cheap portable dipole can be folded and backpacked, carried in use, and adjusted to a very wide range of frequencies.
Note: This is a low power antenna, meant to be used close the body at 5 watts or less. Also, rabbit-ears antennas are not designed to get wet, and the internals will corrode easily.
Let’s go from about minus-12dbi duck to plus-2.2dbi dipole antenna. This one was easily made from spare Sony TV rabbit-ears. First, remove the twin-lead and replace it with RG-174 or -58. Add the appropriate H-T radio connector. Use a permanent marker to mark the rabbit-ear elements at 19-inches extension. Mark the end of the element with red that is connected to the center of the coax, so you can put it “up.” Use 1/2-inch CPVC to make an “L” shape to hold the antenna.
Carry along a pocket tape measure and calculator and you’ll be ready for any f/468 ops!
The basic design idea…
The antenna can easily be folded for storage or packing
You can stick it down the back of your shirt
—73, de KV5R
Variants of this are used for RDF. I myself made a 2 pole 2m phased array but with thick 10 or 8 gauge wire; I realized that, even within a single band, adjustability of everything (conductor lengths and ESPECIALLY their spacing) is critical for the deepest nulls with that type of antenna. I’m guessing that limitation is the reason why yagis (especially tape measure ones) are used by most people as they are far wider banded than this type of array where Q is critical. Of course, if you have room, a shielded mag loop is far superior still.
This is how I made my first contact, replacing my handheld’s rubber duck with this. I also made a lower frequency one for 11m-6m out of telescoping tent poles. The extra bandwidth of larger diameter elements really shows… less SWR despite forgiving on precise pole length. 5/8″ – 3/4″ diameter = way more forgiving than 16 awg wire!