[amsat-bb] Re: Help wanted on CP antenna design
domenico.i8cvs at tin.it
Wed Jul 17 06:16:38 PDT 2013
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
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
----- Original Message -----
From: "Zilvinas, LY2SS" <zilvinas at augma.lt>
Cc: "AMSAT BB" <amsat-bb at 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
> > 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).
> Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
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