# [amsat-bb] Polarity

Burns Fisher burns at fisher.cc
Sat Jan 9 17:39:48 UTC 2016

```Is the -1.5db vs -3db difference power vs voltage (which would be v**2/r
and thus the loss of power is the square of the loss of voltage, which is
double the db) ?

On Sat, Jan 9, 2016 at 12:34 PM, Steve Kristoff <skristof at etczone.net>
wrote:

> 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
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> _______________________________________________
> Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
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> expressed
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```