"Roy Lewallen" wrote
Only a perfect ground ends up creating the same shaped field from a
grounded vertical as a free space dipole.
Real ground creates a field shape which is very significantly different.
____________

A 1/4 to ~1/2-wave vertical monopole used with the typical radial ground
system of MW broadcast stations actually does _generate_ very nearly the
same pattern and peak field as a free-space dipole of twice the length as
that monopole. This has been demonstrated by field measurements going back
to 1937 (George Brown, et al).

It is only after the radiated wave leaves the vicinity of the antenna that
the conductivity of real earth begins to affect it. These effects
accumulate, and at distant ranges, there is more reduction in the groundwave
field than at angles above the horizontal plane

That is why the pattern takes on the shape shown for it by pattern analysis
of this hardware for an infinite distance -- which has zero field in the
horizontal plane. But it doesn't have that shape as it leaves the radiation
system.

RF