At 09:16 AM 12/23/1999 -0800, Al Williams wrote:
>If all of the radiated energy directed towards ground is reflected
>upwards by a "perfect salt water ground", then the skyward
>power can only be doubled--3db. Why then is a salt water
>location so coveted?
Model a vertical with EZNEC over good-quality real ground -- maximum signal
is -0.03 dBi at a 26 degree takeoff. Over very good ground, the gain is
1.26 dBi @ 21 degrees. Model the same antenna over hypothetical perfect
ground, and the gain is 5.15 dBi at the horizon. Salt water is somewhere
in between, of course, but signals at lower take-off angles would receive a
very useful boost.
Maybe you were thinking of horizontal antennas, where the benefit is much
less pronounced. For example, a dipole at 1 wavelength over perfect ground
has a maximum gain of 8.24 dBi, while the same dipole over real ground,
ranging from medium to very good, only drops back to 7.65-7.77 dBi.
73, Pete N4ZR
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