On Apr 26, 5:10*pm, Art Unwin wrote:
On Apr 11, 3:58*am, Helmut Wabnig hwabnig@ .- --- -. dotat wrote:



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.

Helmut
I do not know if the rear signals were as you suspected.,
It is extremely windy here in the midwest for the last few days
so I took off the new dish of it's ground stand and placed the dish in
a corner outside the house with a TOA that I assume is about 10-15
degrees. Again I got rear signals
but I noticed the coverage was very narrow and maybe more than one.
So next two *weeks or so I will repeat the test but also play around
with the elevation
to see if there are other observables to determine if you are correct.
I am playing with circular polarisation which is a new experience for
me and I believe that is capable of picking up reflections that one
does not normally see with planar designs
Best regards
Art

Helmut. Re original thread on dish

I found out what the problem was! The dish itself was in the antenna
circuit thus
the dish was part of the antenna and receiving omni.ie chassis and
ground was the same connection I have discarded the dish experiment
and have gone back to the original design roots.
I can hold it up on one hand stretched out without problems and not
only is it light but also small. Have placed a small cctv rotator and
tipper on a table outside and am now setting up the controls. I
suppose I will have to add a decoder to the motors at a later date so
I can determine positions to follow the band conditions as they
change I do not have a direction indicator so I will wait for a warm
day where I can operate it and seethe position at the same time. The
tipping action will give me control of the skip distance so that
should prove to be very interesting. Anyway, glad that I now have
direction ability back. Tks for your interest.
Regards
Art