"Roy Lewallen"
However, you can't compensate for this factor when the ground is poor by
improving the ground system. The reason is that the reflection takes place
much farther from the antenna than nearly any ground system extends. And
low angle radiation, where the improvement is most needed, reflects the
greatest distance away.
___________

Roy, didn't the experiments of Brown, Lewis & Epstein of RCA in ~1937 show
that the h-plane field measured 3/10 mile from a vertical monopole of about
60 to 88 degrees in height, over a set of 113 buried radials each 0.41 WL,
was within several percent of the theoretical maximum for the applied power
as radiated by a perfect monopole over a perfect ground plane? And
conductivity at the NJ test site was poor -- 4 mS/m or less.

That tends to show that the fields radiated at very low elevation angles
also will be close to their theoretical values when measured at this radial
distance, even though ground conductivity at the antenna site is poor. The
relative field (E/Emax) for radiators of these heights and propagation paths
approximately equals the cosine of the elevation angle.

The greatest radiated fields always will be directed in or near the
horizontal plane when measured/calculated for such conditions. This also
will be true for any monopole from infinitesimal to 5/8 wavelength in
height, although the elevation pattern of monopoles from /4- to 5/8-WL no
longer are described by the cosine function (see
http://i62.photobucket.com/albums/h8...omparison.jpg).

Elevation patterns show maximum relative field centered at various elevation
angles above the horizon, when those fields are measured at progressively
longer radial distances from the monopole, due to the propagation loss for
the surface wave over other than a perfect, flat, infinite ground for those
ranges. Earth curvature and terrain diffraction add to those losses for
longer surface wave paths over real earth, and for very great distances the
h-plane relative fields falls to ~zero.

But that pattern shape is not the pattern shape originally radiated by the
monopole, it also includes the effects of the propagation environment at the
range where it was measured (or calculated).

If this were not true then MW broadcast stations would have essentially zero
coverage area for their groundwave signals.

RF