[amsat-bb] Re: Eagle efficiencies
Gary "Joe" Mayfield
gary_mayfield at hotmail.com
Sat Sep 9 21:25:02 PDT 2006
At some point (not that high in frequency) the beamwidths get so narrow the
antennas are hard to point. Both on the satellite and on the ground. I
don't think a spot beam would be popular with those living outside the spot.
*for a given size* is a biased measurement.
----- Original Message -----
From: "Scott Townley" <nx7u at arrl.net>
To: "Amsat BB" <amsat-bb at amsat.org>
Sent: Saturday, September 09, 2006 2:04 PM
Subject: [amsat-bb] Re: Eagle efficiencies
> Clarification, or more fuel to the fire...
> For a *fixed overall physical size (aperture)*, antenna gain is
> proportional to f^2
> Pathloss is proportional to 1/f^2
> So then the total link budget actually *increases* with increasing
> frequency (f^2*f^2/f^2=f^2), since you have an antenna at both ends,
> subject to the assumption stated initially.
> There are several 2nd-order terms to consider overall, such as decreasing
> transmitter power as frequency increases, thermal/galactic noise
> with freq, etc., but *for a given size* higher is better.
> Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
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