Hi Zilvinas, LY2SS I agree completely with you because the QFH was used for the beacon of OSCAR-7 at 2304 MHz and in addition to be endfire radiation or bakfire radiation it do not require a reflector.
The size of a QFH for 70 cm is very small as you quoted in 264 mm height only and 84 mm in diameter and so it is not very big and weight not to much for a balloon particularly because there is not a reflector in it. I hope that you as well Phil KA9Q and Simone IU1AFY have received my pdf file concerning the QFH written by Walter Maxwell W2DU and another one for 435 MHz written by my self in italian for Radio Rivista 10/1998 I suggest you to read also my article: "Experimental investigation of Quadrifilar Helix Antennas" published by the AMSAT Journal May/June 2004 Best 73" de i8CVS Domenico ----- Original Message ----- From: "Zilvinas, LY2SS" <zilvi...@augma.lt> Cc: "AMSAT BB" <amsat-bb@amsat.org> Sent: Wednesday, July 17, 2013 12:32 PM Subject: [amsat-bb] Re: Help wanted on CP antenna design > > On 2013.07.17 10:11, Simone wrote: > > Hi Phil, > > > > QFH is effectively circularly polarized, it is often used for GPS > > receivers, since when you point it skywards the main lobe points trough > > the zenith, while nulls are pointing to the horizon (where you do not have > > satellites normally). > > > > In my opinion QFH risks to be quite bulky for a balloon, since it will > > occupy a cylinder 1 wavelength high (70cm in your case). > > > > QFH for 70cm band is 264 mm height only (and 84 mm in diameter). > > 73! > _______________________________________________ > Sent via AMSAT-BB@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 _______________________________________________ Sent via AMSAT-BB@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
