skristof at etczone.net
Sat Jan 9 17:34:56 UTC 2016
It makes sense (to me) that it follows a cosine function. So, if your
antenna is horizontal and the signal is at 30 degrees above the horizontal,
you should be getting about 87% of the signal, which figures out to a loss
of about -.6dB. If the signal is coming in at 45 degrees, you're getting
about 71% of the signal, for a loss of about -1.5 dB. If the signal is at 60
degrees above horizontal you'll get about 50% of the signal, which is
the -3dB loss.
At 80 degrees above horizontal, you'll get about 17% of the signal, which is
a -7.6 dB loss
I know that is not what the article says, but if you're going by cosines,
which makes sense to me, those should be the numbers.
(I think maybe)
----- Original Message -----
From: "Robert Bruninga" <bruninga at usna.edu>
To: "amsat bb" <amsat-bb at amsat.org>
Sent: Saturday, January 09, 2016 12:05 PM
Subject: Re: [amsat-bb] Polarity
>> We all know that [matched polarity] = Zero db loss from cross
>> And then in theory, the "Infinite loss" when cross polarized...
>> [Pracically],it's more like 30 to 40 db or so [ or much less in the
> presence of reflections]
>> Now does anyone know of a chart ... for every degree of something really
>> Like 45 deg is 3 db down, 50 deg =? 55 deg =? etc.
> The cosine table works for all angles.. The cosine of 45 degrees is 1/2
> which is -3 dB etc...
> Bob, Wb4APR
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skristof at etczone.com
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