Dave, Phil and Bob,
For additional information read
http://www.w2du.com/r2ch22.pdf
and look at Fig 22-7 page 10 of 20 Radiation Pattern of the 1 1/2 turn 1,25 wavelenght Quadrifilar Antennas.
With the antenna straight up pointed to Zenith the gain is 4 dBi all around the azimuth at 30° elevation and -3 dBi overhead at 90° elevation.
73" de
i8CVS Domenico
----- Original Message ----- From: "Dave Guimont" dguimon1@san.rr.com To: "Phil Karn" karn@philkarn.net; "Bob Bruninga" bruninga@usna.edu Cc: amsat-bb@amsat.org Sent: Friday, August 19, 2011 7:31 AM Subject: [amsat-bb] Re: Turn off AGC when receiving BPSK-1000
You don't have to use a narrow beam antenna with maximum gain on axis. You can always design it with a bowl-shaped pattern that increases gain toward the edges and lowers it in the middle.
That's why the quadrifilars work so well. I measured the pattern some time back, and the "beam width" is about 140 degrees....
Point them straight up and be satisfied with that part of a pass, or mount them at 40 degrees, and rotate AZ with a TV rotor for the entire pass. For 50 degree max passes point them at the center of the
pass...
73, Dave, WB6LLO dguimon1@san.rr.com Disagree: I learn.... Pulling for P3E...
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