Topband: Snow plus vertical
RadioIR at charter.net
Thu Feb 28 10:21:20 EST 2008
>Here's something that's bugging me, and perhaps a few of you fellow snow-cats can give me some advice.
>I'm considering a triangle of MA160V's (Cushcraft) along with radial plates on each. The problem is that here in Southern Colorado, we receive about 4-8 feet of snow during the winter. It seems obvious that I can't ground mount the hot side of the vertical because it will get covered up. SO, I'm going to raise it up by mounting it on top of a steel tube that runs down into the radial plate. It would look sort of like an umbrella stand for your outside patio umbrella.
>I'm not familiar with this antenna yet, but--what will happen if I raise the feed point up? I'm thinking that the 7' tube, being connected to the radial system will work as normal. Will the elevated feed point affect the impedance?
>Any comments on this idea?
>Regards to all,
The extra length at the bottom, between the feedpoint and the radials,
will look like part of the antenna. It will move the resonant frequency
slightly and the feedpoint impedance a little. It's like an off
center-fed dipole, except here it is a vertical and the feedpoint is
tapped higher up on the antenna. It will also create some feedline
common mode currents unless the feedline shield is again tied at the
point where the radials are attached. It should work OK.
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