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Counterpoise Length

been playing with antennas on my SOTA activations, in summer linked dipole, in winter a EFHW trapped for 3 bands. Now playing with random wire antennas so started with the 84 foot wire and the 17 foot counterpoise as mentioned in several books. Want to try shorter wires as put forward as useful lenghts i.e 71 foot and then 53 foot. How is the counterpoise size arrived at, is it a percentage of the radiating wire, or is it too truely random ?


Hi Declan,

I’m a dipole man, but when I looked into trying end fed antennas, it seemed that most sources were staying that a counterpoise need not be very long.

Some reading that might help -



VY 73,

I have had luck with 58/13.


The 84-foot radiator and counterpoise is in fact the classic W3EDP antenna, invented in the mid 1930’s and still popular today. I built mine following an article by G3BDQ in Practical Wireless. According to him the 17 foot countepoise is correct for 3.5, 7 and 21 MHz. For 10 MHz you need a 23 foot counterpoise, for 14 and 18 MHz you only need 6.5 foot, and for 24 and 28 MHz no counterpoise is necessary. For 1.8 MHz, on the other hand, a 126 foot counterpoise is needed, but for that band I use a shorter counterpoise with a loading coil. For 5 MHz I use the 17 foot counterpoise but I have not experimented to optimise it. As far as I know, W3EDP arrived at the counterpoise lengths by trial and error - by all accounts a LOT of error, he is said to have used more than a thousand feet of wire for his experiments!

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I have used a 53 foot radiator and 12 foot counterpoise. How did I arrive there by messing with different lengths in my back yard and it turns out my KX3 seemed happiest tuning it at those lengths. 7m squid pole as support almost inverted L config long end in a tree similar height. On a summit I used it like an inverted V as I did not have any handy trees. Its a compromised antenna compared to an inverted V worked best on 20m, 17m was good to JP1QEC on his summit in JA from my back yard. My best S2S was to Spain from vk5 but that was several years ago not during low point low SFI. Black and red binding post straight into KX3 no coax at all but I have also used a YouKits tuner with short coax lead with ft 817 that works well also 40/30/20m
Ian vk5cz …

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First - This is an antenna/ counterpoise that I’ve only read about, haven’t tried it yet in practice.

About 10-15 years back, I saw an article in a ham magazine (can’t remember which one) that describes an antenna (dipole and vertical wire/counterpoise) made from antenna rotator cable (I think 7 or 8 conductor).

The different wires in the rotator cable were trimmed for different freqs and tuned for the center of the specific freq ranges needed. The wires were not pulled apart from the single rotator cable section, cuts were made at different required lengths. When used as a dipole or vertical/counterpoise, only the two pre-cut sections of rotator cable were needed for multi-band operation.

When used as a vertical/sloper wire with counterpoise, the individual wires in the cable section may have needed retrimming for this configuration; in both the radiator and the counterpoise.

Never got to try it, as usual life intervened. It’s still in the radio plans section of the brain, just needs to be executed. The author did mention that the antenna worked for him with no tuner, but I don’t know about any interaction between the individual conductors; nor the radiation efficiency/pattern.

This MAY work for using a single counterpoise or radiator or both when using a dipole or vertical, but may need a small tuner (ZM-2, SOTA Tuner, SOTABEAMS, etc. ) depending on the current configuration as dictated by available supports. May be useful if the desired radiation direction is in one direction. Or a few rotator cable counterpoise wires could be cut/trimmed to the desired lengths and spread out in different directions.

Again, I haven’t tried this one. Hopefully someone on here may have tried it and can pass more info. It does have the advantage of multiple cut lengths, but is only one physical wire if used as a single wire counterpoise.

Mike, N4VBV

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Thanks for the input guys, some reading to be done and some food for thought