Light,Lazers and HF
Art Unwin wrote:
On Sep 10, 8:45?pm, wrote:
Art Unwin wrote:
What is the main factor that prevents HF radiation from focussing
for extra gain?
Money.
If you can afford to build a 20m parabola about 2,000 feet in diameter
and the place to mount it, you'll get lots of gain.
--
Jim Pennino
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Then are you saying it is the antenna size that is the main factor?.
Of course.
Everyone knows the gain of a parabola is directly proportional to
the size in wavelengths, or:
G=10*log k(pi*D/L)^2
Where G= gain in DB over an isotropic, k ~ .55 for most real parabolas,
D is the diameter, and L is the wavelength (wavelength and diameter
in the same units.
So a 2,000 foot parabola on 20m would have just about 58db gain.
--
Jim Pennino
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