"Denny" wrote
But, I bring us back to the topic, no where do I see HF mentioned
in the quotes from Terman... Ground wave transmission becomes
markedly poorer beginning somewhere around a thousand KC -
which is why hams were relegated to the waste land of 200 meters
and down....
_________

Just to point out that, although groundwave _propagation loss_ is greater
when progressing from lower to higher radio frequencies, the radiation
patterns and peak gains in the horizontal plane from ground-mounted vertical
radiators remain the same for corresponding radiator heights in wavelengths
and equal r-f ground resistances, no matter what the frequency.

All ground-mounted, vertical monopoles through 5/8-wavelength in height
develop maximum radiated relative field in the horizontal plane. If the
vertical radiator is 1/4-wave tall, then the _radiated_ elevation pattern is
approximately a function of the cosine of the elevation angle, no matter
what the ground conditions are, at and near the radiator site.

These are the distinctions I am trying to make, because the common belief
seems to be that the relative field of the elevation pattern launched by a
ground-mounted vertical is dependent on ground conditions, and always zero
in the horizontal plane to peak at some greater elevation angle.

The field strengths measured by Brown, Lewis & Epstein in the benchmark 1937
study defining an effective r-f ground were taken at 3 MHz. And for the
best-case radial ground system the groundwave fields at 3/10 of a mile were
within a few percent of the theoretical maximum possible for that radiated
power over a perfectly conducting earth -- even though the tests were done
in NJ over a path of rather poor conductivity -- maybe 4 mS/m. It's clear
from this that even in the low HF spectrum, the field radiated from their
test antenna over a poor earth path was not zero in the horizontal plane!

RF