"Owen Duffy" wrote
On Tue, 26 Sep 2006 16:22:15 -0500, "Richard Fry"
wrote:
All ground-mounted, vertical monopoles through 5/8-wavelength in height
develop maximum radiated relative field in the horizontal plane. If the

Richard,is this true in general, or is it restricted to perfect ground
(infinite size, perfect conductor, perfectly flat).

NEC models would suggest that the major lobe of a monopole up to 5/8
wave over "real" ground is dependent on the ground characteristics,
and can be quite high relative to the 0deg to 3deg region that people
are focussing upon.
__________________

For the shape of the relative field elevation pattern, it is true in
general. A poor r-f ground for the monopole (i.e., a ground of high r-f
resistance) will change the peak gain of that radiated elevation pattern,
but not its shape.

NEC evaluations typically don't show 100% relative field in the horizontal
plane in the elevation pattern radiated by a vertical monopole except over a
perfectly conducting ground plane, which is the root of all this confusion.

Once the radiation is launched, then it becomes subject to the propagation
losses for the path and frequency. But for verticals up to 5/8-wave tall,
peak relative field always lies in the horizontal plane, regardless of the
ground conditions on and near the radiator site. This is the basis used by
the FCC in determining the coverage capabilities of AM broadcast stations,
and has been proven to be a rather accurate approach going back some 60
years.

RF