Tom Donaly wrote:
Frank's wrote:
The surface or ground wave is the most important fraction of total
radiated power. The correct radiation pattern of a vertical antenna
shows maximum radiation along the ground. Angle of maximum radiation =
0 degrees.

When deducing efficiency, to omit power radiated along the ground from
the hemispherical integration will result in serious error.

( Efficiency by NEC4 ) / ( Efficiency by formula ) = 0.38

I can imagine other losses in addition to loss in the radials but to
have the other losses several times greater is a bit much. Where are
these large losses? Are they in the soil surface - the only other
candidate?
----
Reg.

Correct Reg, I had thought the modified RP card
considered ground wave, but it does not. I am working
on a combined integration including the surface wave,
which should provide a more accurate indication of
the overall efficiency. I will also attempt the
analysis of various lengths of radial wires.

Frank


Reg, with the antenna we have established as our test model:
All wires #14, monopole 9 m, 36 X 10m radials 25 mm below
ground. Ground parameters Er = 16, resistivity 150 ohm-m.
I have calculated the radiation efficiency including the surface
wave. What is interesting is that the surface wave contributes
very little at elevation angles over 10 degrees.

For 100 W input the total radiated power, not considering
the surface wave, is 31 W. When the surface wave is
included the total radiated power is 36 W.

Frank



Good. Now all you have to do is verify your calculations
experimentally.
73,
Tom Donaly, KA6RUH

That's right. Without verification by direct measurements any program
like this is guesswork.

73 Tom