On Apr 10, 10:15*am, wrote:
Dale Parfitt wrote:

"Art Unwin" wrote in message
...
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

There is a lot of very important information missing here.
What frequency are we talking about and what is the dish diameter?
Do you have any idea as to what your edge taper is or sidelobes?

Dale W4OP

The last time he talked about it, it was "designed" to operate on the
160 meter band and the "reflector" was 3 meters in diameter.

No, those numbers are not typos.

--
Jim Pennino

Remove .spam.sux to reply.

That antenna was when I used an old parabolic satellite dish which was
unsuitable.
Scanning past antenna papers point to the use of a cone shape similar
to a horn of 2 metres diameter
produces better results. The antenna needs a longer mast so at the
moment I can't compare
F/R. Either way, with the radiator within the reflector envelope it is
difficult to understand what creates
a rearward lobe regardles of scale or frequency of use with respect to
receive. At the moment I see nothing that points away from the
Rutherford particle experiments with foil .ie penetration when at
right angles , deflection at other angles.