> 120 radials might make a huge improvement with a single
> band vertical on 80 or 160
I've never seen a system where that happens. Almost 100% of
maximum FS in any soil condition come with the first 40 or
50 radials, assuming they are at least 1/4 wave.
The 120 radial myth comes from the BC industry where the FCC
allows stations to short-cut certain complex field strength
measuring requirements if they use 120 radials 1/4 wave
long. Somehow people seem to think the FCC bases that on
performance changes, but it is really all about taking the
worse situation and overkilling it by a factor of two.
A lot of this is just subjective emotional opinion. Very few
people actually measure anything meaningful, but when they
do the general trend is you lose a few dB, perhaps 2-6dB,
with a sparse elevated system close to earth and once you
get the 40 radials or more it doesn't matter if the system
is in the air or on the ground.
99% of antenna talk is really about how the antennas make us
feel, not how they actually work.
73 Tom
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|