Hi Amsat's For a homebrew polarity switch I suggest to read my article: "Switching Four Polarizations on a 70 cm Crossed Yagi"
Part-1 in AMSAT Journal March/April 2007 Part-2 in AMSAT Journal May/June 2007 The above switching circuit allove to switch 4 polarizations V-H-RHCP and LHCP on a crossed yagi having the elements spaced 1/4 wavelenght over the boom and dimension of the feeding and delay lines can be scaled for 144 MHz or any other band. If someone is interested on it I can send a zipped pdf file of both the above articles. 73" de i8CVS Domenico ----- Original Message ----- From: "Art McBride" <[email protected]> To: "'Nick/KB1RVT'" <[email protected]>; <[email protected]> Sent: Saturday, July 31, 2010 6:14 PM Subject: [amsat-bb] Re: Re; Homebrew Polarity Switch > Nick, > The circuit you referred to can be simplified. The two 1/4 wave 75 Ohm coax > sections match the two antennas to 50 Ohms. A 1/4 50 ohm line will delay the > signal by 90 degrees for circular polarization. The opposite rotation is > accomplished by adding of a 1/2 wave 50 ohm section to delay one side by 180 > degrees. Further simplification when using crossed Yagi's is to space one > Yagi a 1/4 wave behind the other and use only the 1/2 wave section. > The end result is to have one antenna lead or lag by 90 degrees for RH or LH > rotation. > To make this work both antennas must be the same electrically and any feed > line after the matching sections must be identical lengths to the antennas. > All wavelength calculations use 2952/frequency in MHz times the VP of the > coax for a 1/4 wave in inches. Multiply by 2 for 1/2 wave. > Experiment and build your own. > Amateur radio is learning by doing! > > Art, KC6UQH > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of Daniel "Nick" Kucij > Sent: Thursday, July 29, 2010 9:11 AM > To: [email protected] > Subject: [amsat-bb] Re; Homebrew Polarity Switch > > > 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. > > > > > > > David, > > PA3GUO has described a homebrew switch on his website, > http://www.pa3guo.com/ > Click on Antennas, then scroll to the Polarity Switch button. > > Nick KB1RVT > > > _______________________________________________ > 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 > > __________ Information from ESET NOD32 Antivirus, version of virus signature > database 5324 (20100729) __________ > > The message was checked by ESET NOD32 Antivirus. > > http://www.eset.com > > > > > __________ Information from ESET NOD32 Antivirus, version of virus signature > database 5328 (20100731) __________ > > The message was checked by ESET NOD32 Antivirus. > > http://www.eset.com > > > _______________________________________________ > 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
