At 11:22 AM 1/3/2006, Tim Duffy K3LR wrote:
>Hi Mike!
>
>I think both systems would give you outstanding results!
>
>My current 160 antenna has lots of radials (120 per element (5) that are 1/4
>wavelength (137 feet) long = 75,000 feet of wire (radial wires intersect with
>buss wires and strap to conserve wire)). GROUND mounted radials under all
>elements are very important for this antenna to work. As mentioned in the
>ON4UN
>book, it has great F/B (32 dB at its peak) and has as much gain as a
>traditional
>full size 4 square array. It is easy to match and assemble, however the
>useable
>F/B is limited to about 50 KHz (a good 4 square would have more F/B
>bandwidth).
>The parasitic system requires less real estate than a 4 square.
An interesting tradeoff appears here. Bandwidth vs directivity. If you
allow adjustable matching & phasing elements (or adjustable elements) you
can get both really good F/B AND operating bandwidth. It's the same as the
"steppIR vs fixed beam" discussion.
There's a lot to be said for a system where it's install and forget. You
do all the hard work during install, and then, just sit back and
operate. Of course, a computer controlled system could do the same.
Jim, W6RMK
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