Tom Hellem wrote:
"I think the reasonable conclusion is that a center fed vertical dipole
is a very difficult thing to make work..."
Tom, at my last QTH I dropped a 40m dipole vertically from a tall
eucalyptus. I fed it directly with RG-58 (no choke). The feedline ran
roughly horizontal for tens of feet. (The tree was slightly down the
slope of a hill from the shack.) SWR was fine. I remember generating
pileups during Field Day as a 500 watt home station, but otherwise I was
not that impressed with its performance.
The gain and elevation pattern of a vertical antenna are quite sensitive
to ground quality. Unless you have really good ground, a horizontal
antenna may perform better, even at low angles, if you can put it at a
decent height. "Decent" might not be that difficult at 14 MHz and above,
but it may be a problem below.
When modeling a vertical antenna, these generic ground constants are
much more appropriate than those your antenna analysis program offers:
https://k6sti.neocities.org/hfgc
Brian
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