On Aug 10, 11:37*am, "Ralph Mowery"
wrote:
"P.R.Humphreys" wrote in message

...

Off subject I know but as a matter of interest what happens to a TX CP
antenna with a clockwise *twist transmitting to a RX CP antenna with an
anticlockwise twist, over short to medium vhf/uhf paths, I would have
thought a reduction in signal ?

Pedr GW6YMS

About the same as going from a horizontal to a vertical antenna. * You loose
about 20 db of signal.
One thing a CP signal will do that a horizontal or vertical signal won't *is
to reverse when it bounces off an object. *That is if you are doing moon
bounce *and send up a signal using right hand CP , your receiving antenna
will need to be left hand CP or you loose lots of db of signal.

Also on the satellites it is helpful to be able to change the CP *from left
to right as the signal sometimes reverses depending on the angle the
satellite antenna is pointing as it passes over.

Do you ever get to the point that your signal bounces off the upper
layers instead of passing thru? I note that some users of the vhf have
seen ducting effects (temp inversions?)