Maybe it is QTH-dependant and I don't know what the models say, but in A/B
tests I've found ground-mounted verticals with 120 1/2-wave radials perform
significantly better than elevated verticals with 4 radials.
I use that configuration for a 40m 4-square, 80m 2 element, and single 160m
vertical. I have a LOT of wire out there (~30,000ft for each system) and
laying them all out and nailing them down (to the contour of the land) was
an enormous task. Not having to do all that work would a big advantage if
it actually performed as well, but I've not found that to be the case.
Tom, NI1N
----- Original Message -----
From: Jim Jarvis
To: towertalk@contesting.com
Sent: Sunday, June 12, 2005 12:39 PM
Subject: [TowerTalk] Ground Planes vs. ground mounted verticals
I have often wondered whether elevating a vertical has any advantage over a
vertical on the ground with a good radial system. "Good being defined as 40
or more radials, 0.2 wavelength or longer at the lowest frequency....de N4OO
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The last few issues of NCJ have addressed the issue of elevated radial
systems and have covered the effectiveness of them compared to ground
mounted
systems. Unfortunately there is no black and white answer as to which is
the better
way to go for the individual operator. It depends on location, what kind of
soil you have, how many radials you have and how high you can get the radial
system. Bill K4XS
-0-
Bill's observation is correct. I no longer get NCJ, so was unaware of the
articles. However, the tradeoff has always seemed to me to be determined by
factors outside our control.
That is, elevate the vertical, and you'll reduce the immediate ground system
losses. On the other hand, the zone of first-reflection will be moved out,
beyond where you can control it. You'll still have the Brewster angle
effect,
and refraction taking place, but it's likely to be on someone else's
property,
and beyond your control. If it's good ground...great. If not...then much
of
your energy will be warming the worms.
That raises a strong argument in favor of ground mounting the vertical, and
putting in a proper ground system. That way, you can control the effects of
earth. But it's a lot of work.
n2ea
jimjarvis@ieee.org
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