This is an antenna that I just built. I intend on using for receiving the AO-27 downlink (at 436.800 +/- doppler). It is built with right hand circular polarization, and the gain is supposed to be in the neighborhood of 3 DB. I don't know what the actual gain of this one is, as I have no way of measuring it. I also expect that I will need a pre-amplifier, as AO-27 doesn't put out much power. When I have done a bit more testing, I will post the calculations for making one.
-- Mike