[amsat-bb] polarity reversal at low elevations

[Estes Wayne-W10191 <W10191@xxxxxxxxxxxx>]

I think Richard Limebear wrote (it's getting hard to tell now):

	Go for RHCP; The only thing you'll lose out on is that, at  > low elevation > (say below > 10 degrees), signals get > scintillated to the > opposite sense so an RHCP signal would get turned round ... > but its not > usually by a complete turn.


Wayne replies:

Interesting.  I never knew about polarity reversal at low elevations.  Is that cause by ground reflection?  If so, it seems odd that the reflected signal would dominate the non-reflected signal.

I use a RHCP yagi to receive FO29, and the 70cm downlink signal usually drops off a cliff below 10 degrees elevation.  I never knew why.  I suppose I might hear wonderfully if I got a polarity switching relay (and a mast-mounted preamp).

I don't remember 2m downlink signals dropping so dramatically below 10 degrees when using a RHCP yagi to receive AO-10/13 or RS-12 (Mode T).

Wayne Estes W9AE
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