Hi Thomas, W9KE In a separate email I have sent to you a very compreensive article explaining why during an orbit of a LEO satellite like FO-29 the changes in polarization is generated.
73" de i8CVS Domenico ----- Original Message ----- From: "Thomas Doyle" <[email protected]> To: <[email protected]> Sent: Saturday, August 04, 2012 4:46 PM Subject: [amsat-bb] Antenna Polarization Technical Question > I had a actual qso on FO-29 the other day and during the contact > circular polarization switching was discussed. > The station I was talking with described a very large change in > received signal strength when switching > between LHCP and RHCP. I have heard other people mention this and I > recall some change when using > AO-10 with my switchable KLM's back in the good old days. > > I have been trying to figure out why there would be such a big change. > Here is a collection of theories/questions. > I would appreciate comments on any or all of them. This is a bit > complex so a direct reply is probably best. > > - In a perfect world if the satellite antenna is linearly polarized > LH-RH switching would not make any difference. > > - In a real world it is unlikely that the ground station receive > antenna is truly circular. It is somewhat elliptical. > > Question: if the receive antenna has an elliptical pattern does the > angle of the major axis change when > switching LH - RH. > This is a complex question related to the nature of what caused the > elliptical distortion in the pattern. > Perhaps someone has measured this. If the angle of the major axis > receive antenna pattern changes when > switching between LH and RH and the satellite antenna is linearly > polarized this could account for some change > in received signal strength. Other than that I am at a loss to explain > why switching LH-RH on a receive antenna > would cause a large change in the strength of a signal received from a > linear antenna. > > > tnx & 73 W9KE Tom Doyle > _______________________________________________ > Sent via [email protected]. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
