[TowerTalk] Choke on feed point of dipole

[Brian Beezley]

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