Rod,
Here's my reply to Dave FWIW.
>Now to the problem.. I plan on installing the antenna on a >30'X30' roof of
a metal building.. Does anyone have a idea >as to how to make/install the
radials?? The antenna will be >mounted on a tri-pod, the roof is about 15'
high, from ground >level..
?
You are quite lucky.? A vertical mounted above a metal building or tin roof
works like gangbusters.? I discovered this several years ago.? I've used the
Butternut both ground-mounted and as an elevated ground plane.? Use
telephone cable and cut one conductor in each cable leg for a different band
for maximum effectiveness as a ground plane.
?
I had an R-7 installed on my tin roof in Moscow at 200' and it performed
almost as well as my A4S on the same roof under most conditions. It was a
killer antenna on 40. (I think the A4S saw the tin roof as ground rather
than the true ground and was affected adversely.) I've used the DX-77 and
R-7's for several years. The Cushcraft R-7 and Hygain DX-77 are half wave
antennas, not 1/4 wave verticals and work best if you can get them up high.
No experience with GAP but friends who have them seem to get rid of them
rather quickly quoting poor performance or fragile construction.
Jon Hamlet, W4ZW
Casey Key Island, Florida
"A little bit of paradise in the Gulf of Mexico"
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