Is a Compromise Antenna Efficient Enough?

If you read online antenna forums, and maybe watch a few YouTube videos, you may begin to doubt whether you will ever find the perfect antenna. Here is a word to the wise – there is no such thing! But there is an old adage that says something like: “the antenna you put up always works better than the one you don’t put up”.

“the antenna you put up always works better than the one you don’t put up”

Out in the field I like using vertical antennas. They have a small footprint, which is important when sharing a public space with other members of the public. Vertical antennas also have a low take-off angle which is helpful in getting DX QSOs. But there are drawbacks and spending too much time on the Internet is likely to make any ham doubt the their usefulness.

I recently came across another one of those online forum opinions that a vertical antenna should have at least 60, maybe 120 radials. Based on what? Then I watched an excellent video by Tim G5TM called “How Many Ground Radials Do You REALLY Need?” Tim talks about the connection between number of radials and efficiency for a ground-mounted vertical antenna. He is absolutely correct and his meticulously researched information backs up his conclusions.

But then I ask myself: “how have I been able to make over 2000 QSOs using a ground-mounted vertical antenna with only 4 radials?” Most of my POTA activations over the last 2 years have been made with that antenna. The answer, of course, is: “the antenna you put up always works better than the one you don’t put up”. Is a compromise antenna efficient enough? Well if you can make contacts with it then heck yes.

Is a compromise antenna efficient enough?

Well if you can make contacts with it then heck yes.

But wait, it gets worse. Another excellent YouTuber is Jim KQ8E. I came across “Jim’s Cool Stuff” quite recently. Jim is an older ham with a very mature and pragmatic approach to the hobby. I immediately liked that he didn’t begin his videos with “hey whassup guys”. But Jim made me think very deeply about why my field antennas should not be working as well as they apparently have been doing for the last 20+ years.

Jim reinforces Tim G5TM’s view that a large radial field is required for an efficient ground-mounted vertical antenna, but he proposes a simple solution. Why not raise the base of the vertical above ground to make it a Ground Plane antenna? A Ground Plane antenna is a vertical antenna with as little as 4 raised, tuned counterpoises. That makes sense. But then again such an antenna would be a monoband antenna unless it had separate counterpoises for each band – and a variable loading coil.

Some time ago I built a loading coil with a variable sliding tap for my ground-mounted vertical antenna. It is wound with stainless steel wire which, according to Jim, is 41 times less conductive than copper. And the sliding tap? That makes an imperfect contact with the stainless steel coil. Overall, my loading coil is just a dummy load that generates heat instead of RF. But Jim, I make contacts with it don’t I? Again, is a compromise antenna efficient enough? My experience says: “heck yes”.

Harmonic distortion exceeding FCC regulations!

Ok Jim, sometimes I use my End-Fed Half Wave (EFHW) antenna instead of the ground-mounted whip. Is that okay? Jim says “no, that 49:1 autotransformer wound on a ferrite toroid core can easily overheat due to hysteresis and start generating harmonic distortion that exceeds FCC regulations”. Oh dear, that’s a bit of a crushing revelation. Ferrites are used in many antennas, either as the core of an RF transformer, or in a Common Mode Current Choke.

I have my own “downer” to add to Tim and Jim’s. A ground-mounted vertical quarter-wave antenna has it’s high current node at its feedpoint. Since the high current point is a point of maximum radiated power (P=i^2*R), isn’t a ground-mounted antenna going to suffer from even further ground losses?

So, for a vertical antenna, we have a choice of solutions and none of them are perfect. Ham Radio Outside the Box readers may be able to suggest more, your comments are welcome.

• A Ground Plane antenna: Lower ground losses but not quite as easy to deploy in a field expedient, temporary installation
• An End-Fed Half Wave antenna: the maximum current point is half way up the mast, but remember to keep that toroid cool!
• Rybakov: a vertical random wire supported by a fishing pole. The high current point is somewhere up the mast, depending on which band is being used, but requires radials.
• Tuned Transmission Line Trap (T2LT, aka Sleeve Dipole): a proven performer, also with the high current point halfway up the mast, but it is strictly monoband.
• Keep Calm and Carry On, remembering that “the antenna you put up always works better than the one you don’t put up” and, a compromise antenna is efficient enough if you can make contacts with it!

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