That statement is completely true as far as it goes, but I think it is
possible to get a 1.1 SWR with a vertical portion that is electrically
longer than 1/4 wavelength and radials that are somewhat shorter. The
combination can still be resonant but the feedpoint is essentially
"off-center" to raise the impedance. I've modeled that in EZNEC and
verified it in practice with roof-mounted "ground plane" antennas I had
at my previous QTH.
I'm not saying that's what John has ... just making a general comment
for clarification.
73,
Dave AB7E
On 3/20/2014 10:54 PM, Jim Brown wrote:
On 3/20/2014 4:40 PM, john nistico wrote:
I have put up a 80 wire vertical in some trees seeing I do not have a
tower. I cut it 62ft6in so it should be on 3.750 however it seems
long and the swr is 1:1 at 3550 or so. I have 10 radials and my
longer version worked just fine. Any feedbck would be helpful.
Hi John,
If you have 1:1 SWR with a resonant quarter wave vertical, you have a
poor radial system. The resistance at resonance of a quarter wave is
about 35 ohms with an ideal radial system. That means you have 15 ohms
of loss in the radials. 1:1 SWR is NOT a design objective for a
quarter wave vertical! Instead, I would work on improving the radial
system. Either a LOT more on-ground radials, or raise the radials as
high as you can.
73, Jim K9YC
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