TheRadioBoard

Hi Guys,

While pondering the inside of my eyelids last evening I had an idea about a vertical antenna. We've all seen or read about folded monopoles, which basically are half of a folded dipole. Some use an existing tower and drop a wire down from a yard arm a few feet from the tower leg.
In my own case, I've already got a lot of ropes and things hooked onto yard arms, so no chance of adding yet another wire. However, what would happen if I dropped a wire down INSIDE of the tower. Electrically, it would be the same, with the feed wire going up and the three
tower legs being the other half of the monopole. Is my idea sound? Any suggestions?

73, J.B., VE3EAR

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To be where I am, I had to leave where I was!

You'd do as well using the tower as the second element, rather than trying to couple into it with a dangling wire. It would be nearly impossible to calculate the impedance that way, but it would be hard to calculate either way, as the tower is probably not a multiple of quarter wavelenghts tall. An elevated vertical will work pretty well with only two radials, but with none, the elevation angle will be very high, and that defeats the main advantage of a vertical.

What band? I've had great QRP success with wire verticals and two radials, with the base of the antenna about 3 M above ground. South Florida to the Middle East on 40 M CW at my sunset, and all continents on 20 CW -- all portable -- for example (rig is an Elecraft KX1). Maybe you can find another place in the yard to place it.

73,

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http://kr1s.kearman.com/
http://qrp.kearman.com/

Last weekend a few amateurs had a really long vertical, a wire connected to a kite. The kite was hanging almost directly above the shack at a hight of 600meters. The performance was 200% ,..if you have a 3wavelength vertical in 180meters.
The same way marconi did it.

Frank

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www.pa2mrx.nl

Jim, Frank,

Thanks for your replies. I was thinking of it as another antenna I could use with my xtal radios, so getting a perfect match is of no concern. You can never have too many antennas! I've got to do something with my three acres of back yard!

73, J.B., VE3EAR

_________________
To be where I am, I had to leave where I was!

Most human-generated noise is vertically polarized, so verticals make poor receive antennas. For a small space, the best broadcast-band antenna is still the high wire. At reasonable lengths they're too short to be very directional (there are always weird lobes, but no strong discernible pattern), and being close to the ground (in terms of wavelength) can be an advantage for reducing noise pickup. You might consider an untuned loop of large dimensions, fed with open-wire, if you have a tree out back to hang it from. If you get it away from the house and other conductors it could make a super signal-snatcher.

73,

_________________

http://kr1s.kearman.com/
http://qrp.kearman.com/