A Simpler Field Expedient Rybakov Antenna for Winter

I recently received an email from Frank Barnes W4NPN who maintains an excellent website with an index of downloadable issues of the Hot Iron Newsletter. The latest issue contains a link to a PDF document from the late G3XBM that discusses a commercial Rybakov antenna manufactured in the UK (no longer available) called the X80. The X80 was a free-standing 5.8m whip tunable from 3.5-29MHz. This prompted me to explore the idea of making my own version.

But first, a question: can we even call this a Rybakov antenna any more? The name refers to a random length vertical wire supported on a fishing pole. Rybakov is said to derive from the Russian word рыболов meaning “angler”. But take away the fishing pole … ?

So what is the reason for redesigning this popular antenna anyway? In a word: winter! It is snow season here in southern Ontario … and freezing rain, ice and everything else that’s cold and nasty.

For this field radio operator, rapid deployment is priority one – rapid deployment with the least discomfort possible.

My Rybakov has been a faithful friend for the last few months. Several POTA activations have been completed with it. And, since I intend to carry on activating parks throughout the winter, my Rybakov had to undergo a little seasonal modification to keep its job.

Why change a good thing? Well, the telescopic fiberglass pole is the main issue. It is supported using three guy lines and three mil surplus aluminum tent pegs. These tent pegs are excellent at holding fast in soft ground, but in winter the ground isn’t so soft – in fact by February the frozen soil resembles concrete. And besides, the frozen soil is often buried beneath a couple of feet of snow.

Secondly, telescopic fiberglass poles have a propensity to collapse, meaning each section collapses down inside the next lower section in a chain reaction that reduces the height from 30 feet to 4 feet in a fraction of a second – and makes an alarmingly loud crash as it does so. To prevent this, I ensure that each section is securely locked into place by pulling and twisting it against the friction surface of the next lower section. Freezing cold weather conditions actually help because the fiberglass contracts in the cold. But then … when it’s time to pack up … the sections remain locked together! So, to make it through the season of ice and snow, the pole had to go.

A few months ago I replaced my worn, beaten and battered MFJ 1979 17ft telescopic whip with a brand new whip shipped on a slow boat from China. It is 18.5ft long – an unusual length but the odd length sparked an idea. Suppose it is erected it at its full length and fed through a 4:1 unun – like a Rybakov? Will it work? I tried it and it tuned okay on all the bands from 40m to 10m. But it’s a very short random length for HF; could it be made more efficient?

I also had a 24 inch length of aluminum tube with a 3/8x24tpi male stub at one end and a small coil of 2.1 microhenries with a female 3/8x24tpi stub connector at the other end (a remnant of an old antenna experiment). Mounting the 18.5ft whip on top of this tube gave an overall length of 20.5ft – not much improvement, except the coil extends the electrical length.

The coil comprises 12 turns of 24ga enameled copper wire wound on a short section of 1/2-inch schedule 40 PVC pipe. A 3/8x24tpi female-female stub fits tightly inside the pipe (a little help from a heat gun makes this easier). The PVC pipe fits snugly inside the aluminum tube. A self-tapping screw at each end connects the lower aluminum tube and the 3/8x24tpi stub to the coil windings.

Plugging the measurements into the quarter wave Coil-Shortened Vertical Antenna Calculator at 66pacific.com revealed the resonant frequency is 9.05MHz – well outside the ham bands thus maintaining its random length cred. To verify this I set my LDG Z-11 Pro tuner the task of finding a match on every band from 40m up to 10m, which it accomplished without difficulty.

What is its electrical length? A bit of simple math is needed here. We can determine its electrical length using the quarter wave formula 234/f which evaluates to just under 26 feet – perfect, that it is right in the zone of a typical Rybakov antenna. Note: the quarter wave formula can be used since we have already established that it would be a quarter wave at 9.05MHz i.e. outside the ham bands and therefore a random length.

Build Your Own? It isn’t necessary to duplicate this design. In fact any whip could be used so long as the coil inductance is adjusted accordingly.

So what have we gained? The wild and wonderful winter whip can be mounted on a single modified ski pole. The pole I use is made from hardened aluminum and has a nicely tapered point that can be driven into semi-frozen soil. When the ground freezes hard, later in winter, it can be mounted on a tripod. The telescopic stainless steel whip can be set up in seconds; in fact the whole antenna can be deployed with minimum exposure to the winter weather. We are now Quebec Romeo Victor for a winter POTA activation. Watch out for my callsign (VA3KOT) on the sked page at pota.app. I hope to catch you on the bands.

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