On Dec 25, 10:58*am, "KC8QJP" wrote:
"Dave" wrote in message

...

"Art Unwin" wrote in message
...
Since we are at the low sun cycle I shoose
1" hexigon poultry wire for the mash on my 3 metre dish
At what frequency will there be a noticable effect on aperture
starting with top band?
Many thanks
Art KB9MZ...,XG

where did art go??? *i need a good laugh!

art deco?

mary xmas

Update
I have made the dish using 1 inch poultry fencing.
The outline of the dish encloses the backfire antenna i.e. the
antenna finishes at the same datum line
as the periphery of the dish. The reason for this is that I am trying
to obtain a zero plus take off angle or
something less than normal with respect to frequency and height using
a planar design
Placed dish on ground with beam pointing upwards and did a swr graph
from 2 to 20 mhz
Repeated above except dish placed at right angles to earth.
Swr for 14 meg hz rose from 2:1 to 3: 1 but both arrangements followed
the same oscillation of SWR.
Difference probably due to variation in dish efficiency.i.e the first
set up was augmented by the ground surface.,
Haven't added the band frequency selection points as yet.
With the graphed impedance curves being similar I am anticipating a
TOA of around
5 degrees when antenna is raised to around 30 feet
Antenna polarisation is horizontal, verticle and cw cwith respect to
gain polarization all being equal in gain, with total gain
being close to 2.5 db in excess of the other polarizations.
As I stated ,the idea is to lower the TOA from that of a normal planar
design.
Comments welcome as well as thrown rocks and sarcasm. I have modeled
this type of antenna pointing straight up
but not in a horizontal plane which is why I was able to sugest gain
comparables.
Regards
Art