"Roy Lewallen" wrote:
... the gain of a resonant (~0.24 wavelength) high vertical at
7 MHz with "average" ground is -0.0 dBi at an elevation angle of 26
degrees. Changing the height to 0.625 wavelengths produces
a maximum gain of 1.19 dBi at 15 degrees elevation angle...

Thanks for your comprehensive, civil analysis. It appears either that my
incarnation of NEC-2 doesn't deal with this situation properly, or I didn't
use it right (the latter is more likely). I'll have a look into it.

In all the cases I looked at, however, the 5/8 wave vertical
did show some gain over a quarter wave vertical up to at least 14 degrees.
...Over average ground, the gain difference is at or just above 3 dB up to
about 10 degrees.

.... which supports my contention earlier in this thread: The peak gain
increase between a 1/4-wave and a 1/2-wave or 5/8-wave vertical is 3dB above
the gain differences of those antennas as dipoles of _twice_ that length in
free space.

Repeating the reasons for this...

* the electrical length of the vertical is doubled by its image below the
ground plane (a 1/4-wave vertical monopole becomes an electrical
1/2-wave dipole)

* the peak "free space" gain of the monopole and its image is increas-
ed 3dB, because all radiation from it is confined to one hemisphere
(above the ground).

RF