Uh, uh,
Wait until Richard Clark sees this and descends on you!!! :-)

Reg,
you can't just look at HF waves propagation through simple "reflective"
glasses. There is considerable amount of propagating going on by refraction,
ducting, polarization gets all tumbled around and ground conditions vary so
much that even those orderly, same current in a loading coil believers get
drowned. There are some propagation prediction programs that will do some
predicting +- 59%, but that's about it. Otherwise as W7EL says, if you are
looking at the antenna pattern forming properties within few wavelengths you
need to consider polarization and ground conditions within the zone, but
once you get beyond "first hop" you are on the mercy of propagation Gods.
You can look at my oooold article
http://members.aol.com/ve3bmv/bmvpropagation.htm
which at the time was judged "ridiculous" and "nothing new" at the same
time. Now a days, especially low band crowds are coming around and admitting
that there is perhaps more refracting/ducting than reflecting going on and
trying to figure out when, why, how.
W8JI fought another losing battle claiming that there is no high angle
propagation on extreme DX signals on 160/80, or skewed path. Now he is
"guru" on the subject.
Soooo, depends.... what you are after? For "regular" conditions you can
apply some ballparks, but for extreme DXing and weak signal comms, there is
whole different world outside of formulas.

Yuri K3BU, VE3BMV



"Reg Edwards" wrote in message
...
The amplitude and phase of a field after ground reflection depends
on
the polarization, and is quite different for horizontal and
vertical. It
of course also depends on ground conductivity and permittivity,
frequency, and angle. The equations are simple, and can be found in
Kraus and other references. Those equations are used by NEC for
determination of the far field pattern.

Roy Lewallen, W7EL

===========================================

Yes! But what's the ball park, rule-of-thumb value in dB ?
----
Reg