Earlier in another thread I posted the text below, and thought it
would be useful to show some documentation for it, and also
give it more visibility.

QUOTE The point I'm pressing is that ground-mounted verticals
up to 5/8-wave high used by ham operators have the same
elevation pattern shapes as those used by broadcast stations.
The peak radiation launched from all of them occurs in the horizontal
plane, and reduces slowly and smoothly for low elevation angles
above the horizontal plane. It could well be that the DX you do work
results from radiation at a much lower elevation angle than believed
possible when looking at the usual NEC calculations and plots for
that vertical antenna. END

The link below leads to a scan of a graphic from Section 10 of
Terman's Radio Engineers' Handbook (1943). It shows the "takeoff
angles" needed to serve various distances from a ground-mounted,
vertical monopole radiator via skywave, and the resulting skywave
fields there for the conditions stated. The reflection coefficients
apply to the E-layer.

Terman's work shows that the elevation pattern of such a radiator
over lossy earth does not approach zero field near the horizontal
plane -- as is a common interpretation when looking at their NEC
evaluations.

Terman's text (p. 743) also states that the reduction in skywave field
after a peak at ~160 miles results from the ERP at elevation angles
serving those ranges not compensating for the greater losses of those
longer paths.

But the skywave fields at 1000+ miles and takeoff angles of 1 degree
and less are far from approaching zero (no matter what we think NEC
is telling us).

http://i62.photobucket.com/albums/h8...ermanFig55.jpg

Discussion invited...

RF