I call it "electromagnetrickery". You can learn a lot by building your own antennas, much more than if you buy commercial ones. But beware, it becomes addictive - I have a drawer full of empty wire spools to prove it. Sometimes the behaviour of those pesky electromagnetic wavicles delivers unexpected surprises. Here is the story of one such surprise I encountered recently.

I was looking at my QRP outdoor field operations backpack wondering why it's getting so heavy - and complicated. Maybe I'll write a post on what goes into that backpack some day. But one thing grabbed my attention immediately - too many antennas. When the urge to get outdoors and play radio edges above the desperate need to go cut the grass, that backpack gets thrown in the truck and off we go.

Which antenna will be needed for today's trip? Who knows, so the best plan is to take them all. That means multiple bags full of wire, RF transformers, ununs, baluns, connectors, spare connectors and ... It was all just too much. Something had to be done. That was when I had an "aha" moment.

Running down the road trying to loosen my load

I looked at all those little baggies stuffed with wire and shook my head. "There has to be a better way" I thought to myself. "Hey just a minute, I've got an idea". I had to sit down for a minute and think carefully. Too many mistakes are made through rash decisions. "Take it easy" I said to myself. "Slow down, you move too fast, got to make the moment last" said my inner self. Well, the heck with that; I don't do slow.

BNTECHGO wire - highly recommended for portable antennas

I hastily pulled two antenna bags (I use small freezer bags; they are strong and weigh next to nothing) out of my backpack and looked at them. Inside one was 25 feet of BNTECHGO super flexible wire for my "Long Tall Sally" 20m band stretched ground plane antenna. Inside the other bag was ... 25 feet of BNTECHGO super flexible wire for my multiband "Rybakov" antenna!

Long Tall Sally versus Rybakov

Long Tall Sally and the Rybakov are identical above the waist; the only difference is in their legs. Both use a 25 foot long radiating wire and a 4:1 transformer above the feedpoint (the "waist") and both are erected as a vertical antenna. Things change below the "waist". The "legs" - i.e. the radials are quite different.

4:1 transformer used with either antenna

Long Tall Sally is a stretched ground plane, single band antenna. A quarter wave ground plane usually employs equal length radiating and radial elements. By stretching the radiating element we can significantly shorten the radials. My own build replaces the usual 17ft radiating element with a 25ft wire. The ground plane radials shorten from 17ft to a little under 5ft. For field expedience I use only 2 radials to allow the whole antenna to fit within two dimensions - useful for operating at the side of a trail without causing an obstruction.

Originally, I used an L-match tuner to match the higher impedance at the feedpoint of Long Tall Sally. But, as some astute readers have observed, the feedpoint impedance is quite close to 200 ohms so a 4:1 transformer makes the use of a tuner unnecessary. It also makes Long Tall Sally look identical to a Rybakov "above the waist".

Coax choke - 3 turns of RG-319 through each of two snap-on ferrites - reduces common mode currents on the feedline

A Rybakov is a short random wire vertical fed through a 4:1 transformer against a radial field. The name reportedly came from the Russian word for fisherman because the antenna is often supported on a long fishing pole. The length of the radiating wire is not critical but I found 25ft to be a good length because it is approximately equal to a 3/8 wave on 20m. I have experimented with various radial arrangements from a single 17ft counterpoise laid on the ground to a set of four 13ft radials on the ground. Common sense suggests the more radials the better but, for field expedience, four radials seems to work well enough. A tuner is required because, in common with all random wire antennas, the Rybakov is not resonant on any band.

The Magic Touch

So here is the magic trick. Erect your choice of pole. I use a bruised and battered telescoping fiberglass pole that was once an MFJ-1910 33ft pole - until it fell down against a brick wall and broke several top sections. I repaired it with sections from a crappie pole that just seemed to fit but reduced its length to 29ft.

Now hang a 25ft length of wire from the top of the pole and attach a 4:1 transformer to the bottom of the wire. I built my own 4:1 from a type 2 powdered iron core and telephone wire.

Now you have options:

• Attach two 5ft radial wires sloped at 45 degrees away from the pole. Keep the ends of the radials away from the ground. Voila, c'est Long Tall Sally - a monoband 20m antenna. Incidentally, the maximum current point and hence the point of maximum radiated power (P=i^2xR) extends higher up the pole than is the case with a regular ground plane antenna - and gives way less ground loss than a quarter-wave vertical mounted on a ground spike (for which you can pay hundreds of dollars).
• Attach radials on the ground - experiment with how many and how long - and, hey presto, you gotta Rybakov!

You will notice that when you switch radials to make the magic transformation, that which was Long Tall Sally suddenly becomes non-resonant and has a correspondingly high SWR. Don't panic; it's now a tunable multiband antenna that will work on 40m and up.

It's a simple but effective magic trick that has lightened my backpack and simplified the clutter of little plastic baggies full of wire inside. Since 20m is my most used band for POTA and other operations out in the Big Blue Sky Shack, I tend to set up for that band first. Long Tall Sally allows me to operate without a tuner and has proved to be a reliable and effective performer. But, if I need to try other bands I know I can wave my magic wand and be back on the air - with a tuner - very quickly indeed.

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