Topband: 1/4 versus 1/2 wave vert.

[Tom Rauch]

> I matched the ground mounted antennas with a parallel
resonant circuit, like Tom described. Very easy thing to do.
> I could first not understand why the halfwave design was
clearly edged by the quarter wave design. But i found, that
commercial installations never ever have high impedance fed
antennas close to the ground. That is not for safety
reasons, it must clearly be, because a strong electric field
introduces strong losses in nearby soil, which would be
particularly true for ground mounted antennas.


My own opinion is the wave angle is too low Wolf. I think
the taller vertical confines the field along the lossy soil
at a great distance, and less radiates up away from lossy
earth.

Some of the biggest failure antennas I have used were 5/8th
wave verticals at broadcast stations. We loaded one AM tower
that happened to be a 5/8th wave on 160, and it was poor
compared to a short vertical. In the 1970's I used a remote
transmitter at a tower in a wet black swamp that was 350
feet tall, and my 1/4 wave vertical beat it. A dipole at the
top of that tower was another story. It worked very well in
two directions (20dB down off the ends however).

I do not think it was loss in the antenna, but rather a wave
angle and farfield loss issue. There is no way to prove
that, it is just a guess.

73 Tom