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Re: 2400MHz...

Hi, Jordan.
  There are many good sources of information to help you answer
your questions. The ARRL Microwave Handbook (not either of the
project books) and the "Mode S Book" from AMSAT are good. If you
are interested in P3D (only uplink S-band bird I'm aware of in the
works) look at the "P3G to P3D", that I edited and that is available
through AMSAT.
   You're right to be interested in atmospheric losses in the 
microwave region of the spectrum. It is a complicated function of
humidity, temperature, pressure, etc. Don't worry about it much for
satellite communication, however. As far as antennas, more gain
is always good. Dishes seem to be favored over yagis above 1.2GHz
due to something called capture area. And, for P3D, you better
not put much power into a high-gain array and point it at the bird.
Uplink signals that are TOO STRONG can serious degrade the operation
of the satellite. An important point is that the higher the gain
of the antenna, the more accurately you need to point the antenna
at the satellite because gain and the angular width of its window
are inversely related.
  Coax loss is what you're getting at with the questions about the
converter at the antenna, vs. remote with a preamp alone at the
  All of these issues are covered in the three publications
(collectively) above. You're moving into microwaves, now, and need
to get up to speed on the differences between these freqs and HF.

Best 73's
--Paul Beckmann, wa0rse@amsat.org

P.S If your interested in some interesting experiments to do with
satellites, both ham and commercial, look at the RSGB Satellite
Handbook, available through ARRL.