Dear David In opposition of most common knowledge and post's of Ham's you will not find much benefit in going circular.
If any antenna of a satellite is not pointing directly at your antenna the polarization will be ellipsoid and not circular. I had a system to switch my antenna from vertical to horizontal and circular left and right. Most of the time vertical or horizontal polarization was best. When the satellite raises over the horizon or sets to the horizon, horizontal will be best. Above some angle vertical is better. During the pass the polarity may Change again. Circular was at most as good as vertical or horizontal but never better. The switching circuitry to switch from horizontal to vertical is only a single pole dual throw switch without any impedance transformation. Much more easy to realize and much cheaper too. The promised 3 dB Gain from a circular Antenna I never got. Just a suggestion. Paul HB9OMQ -----Ursprüngliche Nachricht----- Von: [email protected] [mailto:[email protected]]im Auftrag von David Wing Gesendet: Donnerstag, 29. Juli 2010 07:42 An: 'AMSAT BB' Betreff: [amsat-bb] Homebrew Polarity Switch Im looking into making a polarity switch for a ¼ wave offset crossed yagi and am reviewing the write-up in the ARRL Satellite Handbook and the ARRL Antenna Book (pretty much identical articles). The diagram calls for a 1/4 wave 36 ohm transformer as a part of the circuitry. Im having some trouble finding anything like this online. Is this a readily available item? Is it something I should plan on scratch building? There is a picture in the Antenna Handbook and the antenna includes this item and it appears to be a manufactured part. If anyone can point me in the right direction to find this item I would appreciate it. Additionally, if it is something that I could fabricate and there is good info available online, please forward any appropriate links to me. Thanks, David K6CDW _______________________________________________ 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
