"John Smith" wrote
The "beam width" of a quarter-wave has a very wide "acceptance ratio" and
grabs much more reflection from the ionosphere--a half-wave has a much
narrower beam width--it is a "quieter" antenna, but, grabs more of the
signal I am after...
_____________

A 1/2-wave VHF/UHF vertical has more gain at lower elevation angles than a
1/4-wave, but that may not usefully improve the SNR of the system. Most of
the noise power in these antennas doesn't arrive from higher angles anyway,
because those freqs don't reflect well from the ionosphere.

RF