Roger,
Because height above ground affects feedpoint impedance as well
as providing -- ideally -- 6 dB of ground reflection gain, the actual
gain of a horizontal half-wave dipole can be nearly one dB better
than the 8.15 dB you suggested at certain elevation angles.
An excellent reference on this topic -- based on actual measurements --
was published in IEEE Transcactions on Antennas and Propagation, July
1967, pp 569-571.
To summarize the article, the following heights provide over 9 dBi of gain
for a horizontal half wave dipole over perfectly conduction soil. Gain of
a horizontally polarized dipole drops only 2 dB (to 7 dBi) when placed
over poorly conducting soil.
Height in Elevation Angles
Wavelengths exceeding 9 dBi
0.6 16-30
1.1 10-16
1.6 7-11
2.1 5-8
2.6 4-6
73!
Frank
W3LPL
donovanf@sgate.com
On Sun, 19 Oct 1997, Roger D. Johnson wrote:
> If you use an isotropic radiator for the reference and add in 6 db
> ground reflection gain , it's possible for a dipole to have 8.15 db
> "gain" by itself!
>
> 73, Roger
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