"Richard Clark" wrote:
... any radiator from 0.1 to 0.625 wavelengths pretty much
has the same gain in the same direction.
________________

This will be news to the FCC and AM broadcast stations, all of whom
understand that the ground wave from radiators of the heights you mention
above varies WIDELY, as demonstrated by empirical measurements going back
some 70 years.

For example, a 0.1 lambda radiator has about 54% of the groundwave field as
one of 0.625 wavelength, assuming a very good ground system for each (1 ohm
or so).

A matched radiator of 0.1 lambda height would need about 3-1/2X as much
input power as a 0.625 lambda matched radiator in order to generate the same
ground wave field strength over the same radio path.

RF