> 5/8th wave radiators have been known "forever" by the
> broadcast industry as the best for maximum FSM to
> the horizon, at least that is what I have read.
Hi Jim:
All other thing being equal, The 5/8 wave radiator develops more gain than
a half or quarter-wave single radiator. However, since the 1920s, the
broadcast industry has long recognized the importance not of the 5/8 wave
radiator, but rather the 190-degree radiator (slightly more than half
wave).
Early broadcast installations utilizing 5/8 wave radiators were plagued
with the high-angle lobe that emanates from the radiator, thereby causing
skywave interference and skywave-to-ground wave phase cancellation at the
outer edges of the ground wave.
The 190-degree radiator was developed as a compromise gain antenna
(essentially the gain produced by a half-wave vertical radiator over a
ground plane) that maximizes all it's radiated energy toward the horizontal
plane, thereby nearly eliminating the skywave-generated lobe.
Nearly all the big old-time clear channel powerhouse AM stations in this
country today utilize the 190-degree radiator.
-Paul, W9AC
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