----- Original Message ----- From: "Idle-Tyme" <n...@mwt.net> To: <amsat-bb@amsat.org> Sent: Saturday, April 17, 2010 4:51 AM Subject: [amsat-bb] Re: Arecibo and circular polarization using cheap yagis
But what about antennas like the M2 ants where it's a balanced feed, and there is no + side of the element or coax? The Original Rolling Ball Clock Idle Tyme Idle-Tyme.com http://www.idle-tyme.com Hi Idle-Tyme The M2 antennas uses folded dipoles wich is a balanced system with impedance of 200 ohm. In order to transform the impedance from 200 to 50 ohm and change from a balanced system (the folded dipole) to a unbalanced system (the 50 ohm feed line) a 1/2 electrical wavelenght of 50 ohm coax cable called balun is connected with the inner conductors across the dipole studs. the braids of the 1/2 electrical wavelenght coax balun are soldered togheter with the braid of the 50 ohm coax feed line and grounded to the center of the antenna boom. The side of the folded dipole connected to the inner conductor of the feed line is the (+) side of the element. I hope this helps 73" de i8CVS Domenico _______________________________________________ Sent via amsat...@amsat.org. 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
