[amsat-bb] Re: Antenna discussions
k5oe at aol.com
Thu Mar 24 14:25:41 PDT 2011
How about a 3rd school of thought? If you have a clear view of the horizon, I recommend you point the antenna(s) directly at the antenna (0 degrees elevation). That is the point in a satellite's path across the sky where you have the greatest range (distance between you and the satellite) and the bi-directional greatest path loss (not counting any ground gain you will experience if you have horizontal or CP antennas). As the satellite rises in elevation, range and path loss both decrease and you need less gain to overcome noise: a moderate-beamwidth antenna with a gain of 8-10 dBi will match this nicely. A LEO satellite spends the majority of it's visible time below 30 degrees and the pass time above 60 degrees is almost negligible.
If you can't hear the satellite at the horizon with this setup, then you can raise the antenna's angle and listen when the satellite is closer (higher elevation), but you will greatly reduce the available time/footprint and your number of contacts.
Along those lines, before I put up my Kenpro az/el rotor, I plan on testing
various locations using my Elk with a fixed el but on a small rat shack
rotor for az. I have seen here recommendations for 15 deg and some for 30
deg fixed el. Thus there seems to be 2 schools of thought on this. Is there
any compelling argument for one or the other? I'm almost inclined to split
the diff at +-22 deg. (most passes for me are N/S and to the E - not so good
Any thoughts appreciated
73, Ted, K7TRK
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