On Sep 10, 10:05*pm, wrote:
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:

Not so!,

That is totally depended on the conditions assumed or assumptions made
such as the shape and size of the emmitter from which scattering of
radiation
can be calculated i.e. the shape of the cone if the scattering is
confined to a specific angle.
If radiation is determined from all four forces of the standard model
then the radiator can
be any size, shape or elevation as long as it is in equilibrium, thus
the "weak" force
must be taken into consideration. Period .
This also means one must think beyond the books
where radiation is a mystery and not fully understood by the masses.
Progress can only be made by following the Universal laws via first
principles
and not by selected extractions of formula from reading matter.
Don't they parrot that in the Universities of the U.S.A.?
Best regards unless you are in a nasty mood
Art Unwin KB9MZ..........xg






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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