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 [email protected] 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" [email protected] To: "amsat bb" [email protected] 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 _______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed 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
Steve Kristoff
"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 [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed 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