Hi Domenico,
I received and briefly went trough both articles.
Seeing the front cover scan of Radio Rivista with the orange pipe brought back to my mind that I read that article from the magazine 17 years ago... At the time it was too soon for me to understand anything technical on antennas but the dimensions to build them...
Best 73
Simone - IU1AFY/F4VPY
2013/7/17 i8cvs [email protected]
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" [email protected] Cc: "AMSAT BB" [email protected] 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).
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