Hi Lars, OZ1BXM The shorted quarter-wave coax line suggested in the ARRL Handbook 2008 and 2009 pages 23.20-21 will work great because it is a short circuit for the static electricity and a theoretically infinite impedance at the resonant frequency so that for the RF input signal it is completely ignored by the input stage of a converter or preamplifier.
Remember that a quarter-wave transmission line when shorted at one end shows an infinite impedance in theory at the open end as you can see using the Smith Chart. If you enlarge a shorted quarter-wave by any even or odd number of 1/2 wavelenght of coax line thing do not changes because a 1/2 wavelenght of transmission line represents a full turn of the Smith Chart. Do it as suggested by the Handbook ! 73" de i8CVS Domenico ----- Original Message ----- From: "Lars Petersen" <[email protected]> To: <[email protected]> Sent: Tuesday, August 04, 2009 6:01 PM Subject: [amsat-bb] Avoiding statics on helix antennas > Hello AMSAT list, > > I have a problem caused by static electricity building up on my two helix > antennas (23 cm and 13 cm). Two converters have already been zapped, so I > have to do something about it. > > What measure would you recommend to avaoid statics building up on helix > antennas? > > Does anyone have experience using the shorted quarter-wave-stub mentioned in > "The ARRL Handbook 2008" pages 23.20-21? > > Vy 73, Lars Petersen, OZ1BXM, > AMSAT-Member 36222, > [email protected] > www.oz1bxm.dk > > _______________________________________________ > 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
