On Apr 10, 9:30*pm, Art Unwin wrote:
On Apr 10, 8:45*pm, Tom Ring wrote:



Art Unwin wrote:

The posting is about dishes not antennas. I have not read about a dish
that does not emit signals to the rear. Now I have built one and find
to my surprize that it does accept signals from the rear ! All very
simple, the radiator is resting at the bottom of a cone and the top of
the radiator does not stick out beyond the reflector. Since you do not

Well, to start with Art, a cone reflector doesn't meet the definition of
a dish antenna.

I'm sorry, but they just aren't the same thing.

I surprizzzed you missed the difference.

tom
K0TAR

Tom
I asked the question as I am not personly knowledgable about dish
style reflectors.
I do read a lot and I read a paper once where it was found that a cone
shaped reflector produced increased gain when used with a helix
antenna, so I made one to try it out. Personaly I see it more as a
horn and not as a dish with a radiator at a phase control difference
from the reflector? Either way I do not understand how that I can hear
signals to the rear if the reflector envelope encloses the radiator
thus the question. Note that a helix radiates differently from the
normal dish radiator such that phasing does not enter the design which
is why you see planar dishes or "cups".
Thus questions with respect to reflector diameter are not
pertinentwhen the radiator is enclosed.

Guys
In the absence of a explanation I will provide a possible alternative.
Maxwell added a specific portion to his mathematical laws that refer
to mass and the speed of light thus verifying the existance of
particles. This addition brought statics laws into the radiation
sphere. Rutherford of the UK ( Manchester)showed that particles could
piece a foil of gold because of the relative size of the particle with
respect to the latice make up of the foil when viewed head on. Thus in
the same way a particle or mass ejected at the speed of light from a
radiator could possibly pierce a reflector when met head on.
If so this would explain the rear signals. In the case of a radiator
that is not enclosed by the envelope of a reflector head on deflection/
interaction is quite possible and well understood and there are
designs to avoid it. With respect to dish edges one can see in the
radio handbook what happens to a signal grazing a sharp edge, but that
seems hard to swallow when hams cling to the idea of radio "waves"
when their actions has not been satisfactorily explained with respect
to radiation by physicists.
I suggest that you all pick up the Gaussian equations and add the
presence of a time varying field such that it is mathematically the
same as one of Maxwell's laws ie
look for mass and light speed signatures. We are past the times when
one could suppress ideas such as the World is not flat. When you
finally arrive at the point of understanding of Maxwell you only then
gain an understanding of radiation. With the denial of this
mathematical evidence by all you have zero understanding of radiation
and therefore redundant.
Bye