# [amsat-bb] Polarity

R.T.Liddy k8bl at ameritech.net
Sat Jan 9 22:20:40 UTC 2016

```It seems to me that a live test of these theories and calculations would be easy to perform.
In an open space, separate two radios with dipole antennas. Onone radio transmit and read the receive level on the other radiowhile turning one of the antennas to a variety of polarizations.
Be careful to avoid ground effects and Fresnel Zones.
Let us know the results.   ;o)
GL/73,      Bob K8BL

From: Steve Kristoff <skristof at etczone.net>
To: amsat bb <amsat-bb at amsat.org>
Sent: Saturday, January 9, 2016 12:34 PM
Subject: Re: [amsat-bb] Polarity

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)

Steve AI9IN

----- 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
> polarization.
>> 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
> is?
>> 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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Steve Kristoff
skristof at etczone.com

"A few chords strummed on a ukulele, enough to please a few others beside
yourself, does more good in this world than the combined efforts of all the
financiers and politicians that ever lived." - Frank Littig, Littig's New
Harmony Self Instructor Chords for Ukulele, Banjuke or Taro Patch Fiddle,
Chart Music Publishing House, Chicago, Illinois, 1924

_______________________________________________
Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
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are solely those of the author, and do not reflect the official views of AMSAT-NA.
Not an AMSAT-NA member? Join now to support the amateur satellite program!
Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb

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