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.

Art Unwin wrote:\
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.

He is _awfully_ funny, isn't he?

tom
K0TAR

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

On Fri, 10 Apr 2009 20:05:34 -0700 (PDT), Art Unwin
wrote:

In the absence of a explanation I will provide a possible alternative.
... such as the World is not flat.

Which would, of course, mean that the dish (cone?) antenna?))
radiator?))) is not listening to signals from the back, but those that
have gone all the way around the World to the front to be heard now
with 3dB gain.

Nothing is broken, it is a S U C C E S S. Modern theory has proven
Alfred E Newton right!

Blimey-what. Me Worry, guv? (non Shakespeare, modern English).

73's
Richard Clark, KB7QHC

On Fri, 10 Apr 2009 18:01:17 -0700 (PDT), Art Unwin
wrote:

The posting is about dishes not antennas.

Are you offering recipes now? How to fill a 3 quart mixing bowl with
an imperial gallon of secret-sauce? I can anticipate the amazed
posting of how surprised you would be to find you need a mop there
too.

73's
Richard Clark, KB7QHC

You can argue till you're blue in the face, but in the 50+ years in the radio electronics field, both in civilian and military occupations, I have yet to see a single 'particle' [other than dust, perhaps] on any of the many oscilloscopes I've ever used. Conversely I seen countless 'waves'. I'll stick with the time tested term of RADIO WAVES.

I don't see Art's postings except as they're quoted by others. But from
what I'm seeing here, it looks like he's done a great experiment which
graphically shows that radio waves don't act like particles. More
experiments along this line weren't really necessary, since it's been
known at least since Hertz's experiments in the 19th century. And anyone
who took high school physics and watched the ripples in the ripple tank
should be able to immediately predict what Art is describing. But I
suppose the experiment and its results might prove enlightening for
those readers who didn't take high school physics and who are nearly
completely unacquainted with electromagnetics.

Roy Lewallen, W7EL

Roy Lewallen wrote:
I don't see Art's postings except as they're quoted by others. But from
what I'm seeing here, it looks like he's done a great experiment which
graphically shows that radio waves don't act like particles. More
experiments along this line weren't really necessary, since it's been
known at least since Hertz's experiments in the 19th century. And
anyone who took high school physics and watched the ripples in the
ripple tank should be able to immediately predict what Art is
describing. But I suppose the experiment and its results might prove
enlightening for those readers who didn't take high school physics and
who are nearly completely unacquainted with electromagnetics.


Sorry, Roy, that experiment won't be possible. The bathtub is
permanently occupied by the wannabee Archimedes.



--

73 from Ian GM3SEK

On Thu, 9 Apr 2009 20:05:20 -0700 (PDT), Art Unwin
wrote:

I made a helical end fed antenna that is inside a cone shaped
reflector
The reflector is made from 1/2" mesh steel with an aluminum foil liner
and connected to the braid of the feed coax. No baluns are used, just
direct connections.
I was surprised to hear signals from the rear!
I thought that a dish reflector prevented such signals getting to the
receiver. So what can be wrong with the reflector or can signals get
reflected back from the frontal area? Antenna is at a 40 foot height
Any ideas as to what the fault could be?
Regards
Art
I have no experience with dishes thus the question Note, the helical
antenna does not protrude beyond the dish envelope.
Art
How do you know?
The "rear" signals may come from the front side actually, having
been reflected by your neighbours house, or distant mountains,
or anything in between.

w.

"Art Unwin" wrote in message
...
Seems like the dish
reflector does not get a lot of attention from ham operators !

certainly not by 160m ham operators! welcome back art, needed something to
brighten up a dreary saturday morning!