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With regard to the question by Guy Hamblen about using elevated radials
with a gamma-matched tower:
I have been using elevated radials with a low ground plane vertical on
75/80 for over a year. Tthe antenna is a sloping vertical wire that
begins at 6 feet above the ground, and goes up from there. The
1/4-wavelength radials are at about 6 feet. It is the best-performing
antenna I have had on 75/80. I have ten elevated radials, no ground
radials, and all ten radials are on the east side of the antenna,
because it is on the east side of a hill. I have another gp on the west
side of the hill.
At first I tried a ground-mounted vertical with elevated radials, which
is analogous to what Guy wants to do with his gamma-matched tower. The
approach worked, and led me to the current antenna. However, I noticed
that the ground-mounted vertical appeared to be shortened such that it
looked electrically like it began at the radials, rather than at the
ground. This was a rough approximation, I did not measure the new
resonant frequency, but it had definitely shifted up quite a lot from
where it had been with ground radials alone, when I added the elevated
radials.
Within the past two weeks I put up an inverted-L for 160, also using
elevated radials, along with ladder-line feed. I now have six 1/4-wave
radials on this antenna, and I have managed to work Europe with it. It
is hardly as dominant as the 80-meter gp, and it hears poorly. It works
the US fine. However, time will tell whether it is better than the old
dipole I ran a few years ago. Perhaps I will try a coaxial feedline.
In my estimation, an elevated-radial wire vertical is the 80-meter
antenna of choice for anyone who wants to work 80-meter DX, has a tower
or other 50-foot or higher support, has room for 1/4-wavelength radials,
is a cheapskate, and is single or has a spouse who understands the need
to put out 20 or so wires, 67 feet long, just above head height (by the
way, higher is probably better). This antenna has more DX bang for the
invested buck than anything else on 80 meters at a low-cost height. It
requires a dipole center connector (optional) lots and lots and lots of
wire, an electric-box buss bar to attach the radials, and a feedline.
Jan, KX2A
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