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

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

No baluns are used

That alone is at least one thing wrong with the design.

Ignoring the obvious, the design suffers from the basic disregard for
scale and wavelength.

There are probably other issues beyond these violations of first
principles.

73's
Richard Clark, KB7QHC

On Apr 9, 11:59*pm, Richard Clark wrote:
On Thu, 9 Apr 2009 20:05:20 -0700 (PDT), Art Unwin

wrote:
No baluns are used

That alone is at least one thing wrong with the design.

Ignoring the obvious, the design suffers from the basic disregard for
scale and wavelength.

There are probably other issues beyond these violations of first
principles.

73's
Richard Clark, KB7QHC

The radiator is totally within the reflector envelope !
It is possible that the transmission line is picking up
some signal but a brief scan of the books show that
dishes do some how obtain some signals from the rear..
"Ignoring the obvious" is a nonsense aproach,
as is scale and wavelength.
I was hoping for somebody who is familiar with dish design
and not from one who is a talking head bent on agitation
and slander

On Fri, 10 Apr 2009 06:29:24 -0700 (PDT), Art Unwin
wrote:

"Ignoring the obvious" is a nonsense aproach,
as is scale and wavelength.

This is a curious defense of poor practice. The results fully follow
the obvious problem of ignoring scale and wavelength. Fundamentals
have been violated - it doesn't take a PhD nor a research grant to
figure that out. No models are necessary, but they would show the
failure too.

73's
Richard Clark, KB7QHC

In message , Richard Clark
writes
On Thu, 9 Apr 2009 20:05:20 -0700 (PDT), Art Unwin
wrote:

No baluns are used

That alone is at least one thing wrong with the design.

Do you use a balun with a helix and a dish reflector? Surely that bit at
least is right!





--
Ian

On Fri, 10 Apr 2009 14:35:26 +0100, Ian Jackson
wrote:

No baluns are used

That alone is at least one thing wrong with the design.

Do you use a balun with a helix and a dish reflector? Surely that bit at
least is right!

Hi Ian,

What has been done right is arguable in the face of failure. The
simple testimony easily reveals very simple problems of a fundamental
nature.

Hoisting the design 40 feet only added to the inefficiency of the
exercise (use common sense before muscles - much in the sense of
"measure twice, cut once").

73's
Richard Clark, KB7QHC

On Apr 10, 8:35*am, Ian Jackson
wrote:
In message , Richard Clark
writesOn Thu, 9 Apr 2009 20:05:20 -0700 (PDT), Art Unwin
wrote:

No baluns are used

That alone is at least one thing wrong with the design.

Do you use a balun with a helix and a dish reflector? Surely that bit at
least is right!



--
Ian

Ian;
I specifically mentioned the absence of a balun. I stated that since
it doesn't seem relevent, especially when one reviews published
patterns. In a way I knew that Richard would pile up his postings of
olde english prose in the shape of riddles that provide nothing, But
one has to get used to him and his pals kb9....and others who smear
this group with a foul smell as they are wired very differently from
the rest of us.

"Art Unwin" wrote:
-drivel snip-
In a way I knew that Richard would pile up his postings of
olde english prose in the shape of riddles that provide nothing, But
one has to get used to him and his pals kb9....and others who smear
this group with a foul smell as they are wired very differently from
the rest of us.

Art-let me point out the obvious.... unless your license has
expired, then you ARE a kb9!!!!! Have a nice weekend, glad
to see you back posting on the NG. Things were dull without
you.

Mike W5CHR
Memphis

On Apr 10, 7:38*pm, "Mike Lucas" wrote:
"Art Unwin" wrote:

-drivel snip-
*In a way I knew that Richard would pile up his postings of
olde english prose in the shape of riddles that provide nothing, But
one has to get used to him and his pals kb9....and others who smear
this group with a foul smell as they are wired very differently from
the rest of us.

Art-let me point out the obvious.... unless your license has
expired, then you ARE a kb9!!!!! Have a nice weekend, glad
to see you back posting on the NG. Things were dull without
you.

Mike W5CHR
Memphis

Oh, I have just popped in and saw Richard up to to his old tricks with
Cecil. I don't really expect a satisfactory answer. All on this group
denied it was possible to expand Gaussian law of statics to the laws
of Maxwell so there is nobody with a real feel with respect to
radiation, and of course it shows! Same goes for the nature of Richard
no matter how he tries to hide things. The KB9 station and his foul
mouth friends are what I was referring to and is why they are pleading
for a moderator for this newsgroup. Not really the type I wish to
associate with. When the group deviate from the question at hand is
when I leave as they all eventually do.
Within the next few hours they will want to ask questions about you
know what to cover their ignorance and Richard will come prancing in
again with his long leg mesh underware acting out a shakespere scene .
A few years on a ship tends to change
how you look at life so that he walks in the snow with his foot prints
in a straight line
so that the torso wobbles and then there is the way that he acts and
speak.
My question is still there and regardles of the number of postings
made I doubt that it will be answered. This newsgroup becomes dull
when radio goes out the window and personal attacks begin so one
really gets what he wishes for when they hang around.

In message
, Art
Unwin writes
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?

Diffraction off the edge of the reflector. It causes backlobes. It's
not a fault.

Brian GM4DIJ
--
Brian Howie