On Sep 11, 11:11*pm, "Hal Rosser" wrote:
"Art Unwin" wrote in message

...

What is the main factor that prevents HF radiation from focussing
for extra gain?

1, Focusing the radiation involves using a parabolic antenna whose surface
area is several wavelengths in length
2. Since our definition of HF includes frequencies between 1.8 Mhz and
50mhz, the physical size of the reflector required would be too large for
the average ham to handle.
3. However, that does not prevent HF radiation from being focused, it just
address the practicality concerning costs.
Therefore the answer is: There's nothing to prevent HF radiation for
focusing for extra gain, as long as you build the antenna or beam in
proportion to the wavelengths. If the wavelength is 10,000 times larger than
that old TV dish, then simply build your "dish" 10,000 times larger, and in
the same proportions.

Hal
I have a antenna the size of two shoe boxes. This antenna is multi
wave lengths long
and will radiate on top band. In making this antenna so small I added
inductance
which I consequently cancelled as lumped loads have not been included
in the laws of radiation
as espoused by Maxwell. The opinion of this group is that I place a
reflector at a great distance
from this small physical box and call it a reflector!
I place this same small antenna upon the ground and with the use of a
antenna program
determine that I have produced gain based on a perfect ground. The
design on the antenna
is based upon the laws of Gauss since the laws of Maxwell has not
provided any impetus to the
solving of the phenomina of radiation . The laws of Gauss correlate
with each other and a person came on board
to verify such. But the trail that I offered has been rejected
Not.... because the association presented is in error
it was rejected by.....well..........well just because....... without
providing evidence to the contrary.
This has lead us to the obsurd present point where a cubic foot size
antenna for top band should have
its reflecter a couple of blocks away and of a size stretching for
several thousand feet instead of a few inches
where if the antenna was a ball of presureized water the close
reflector would prevent the jet of water spreading to the rear.
Regards
Art KB9MZ.....XG