Tom,
> What I was wondering, what happens if you put an end fed zepp
> antenna up vertically. Feeding it at the bottom, just like if
> it was horizontal. I'm sure the pattern would be totally different
> from a vertical. You never see an all band antenna like that,
> vertical.
A single band vertical Zepp is called a J-pole.
Once you move away from the single band matching system and end
feed the stub, the take off angle goes up and most of the RF
goes right through the ionosphere never to return.
Assuming a 40 meter "J-pole" with the stubs ending 1 foot above
ground here is what the models say:
Band gain @ 15 degrees max gain @ elevation
40 .96 dBi .96 dBi 15 degrees
30 .38 3.46 30
20 .94 1.23 18 (and 50)
17 -1.17 4.75 56
15 -4.42 7.26 45
12 -3.99 5.98 51
10 1.34 4.34 41
Angles higher than 35 - 40 degrees on 20 meters and 25 degrees
on 10 meters provide very little long distance propagation (see
N6BV and others). If mounted on the ground a 40 meter J-pole
would be 100' tall - I can think of a lot better uses of a
100' tower!
73,
... Joe, W4TV
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