The most comprehensive info on QFH antennas is the Microwave Journal December 1970 Pgs 49-54 By CC Kilgus.
Art, KC6UQH -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of i8cvs Sent: Wednesday, September 30, 2009 5:35 AM To: AMSAT-BB; Franklyn A. Ballentine, jr Subject: [amsat-bb] Re: quadrafilar helix for 70cm- ambiguous design specs Hi Frank, KB1QZH The best starting point is the original article of the inventor of QHA i.e Walter Maxell, W2DU In a separate email I have attached the above fundamental article. 73" de i8CVS Domenico ----- Original Message ----- From: "Franklyn A. Ballentine, jr" <[email protected]> To: "i8cvs" <[email protected]> Cc: "AMSAT-BB" <[email protected]> Sent: Tuesday, September 29, 2009 6:45 PM Subject: Re: [amsat-bb] Re: quadrafilar helix for 70cm- ambiguous design specs I have a question along the same line. Is the QHA in the ARRL Satellite Handbook \ Antenna handbook, a good starting place? Thanks, Frank B. KB1QZH On Tue, Sep 29, 2009 at 11:17 AM, i8cvs <[email protected]> wrote: > ----- Original Message ----- > From: "Tim Goodrich" <[email protected]> > To: <[email protected]> > Sent: Monday, September 28, 2009 9:45 PM > Subject: [amsat-bb] quadrafilar helix for 70cm- ambiguous design specs > >> Hi All, >> >> The house I just bought precludes me from even using my arrow inside as >> there must be something un-RF friendly in the walls. Therefore, I was >> looking for a roof antenna and the October QST article on the QFH inspired >> me to build one. However, after doing some research, I have come up with > two >> sets of design specs and I'm unsure which one is correct. >> >> >> >> I converted everything from you're the 146Mhz QST model to 436Mhz. > However, >> when I plug that info into http://www.jcoppens.com/ant/qfh/calc.en.php >> >> The values it puts out are different in the "compensated length" field. > The >> only difference is this model calculates for a full turn as opposed to a >> half turn, but the lengths shouldn't be as different as it says. Under the >> QST model, I get a wavelength of 688mm, but under the website's model, it >> gives me a "compensated wavelength" of 729mm. >> >> >> >> The values I used to calculate are: >> >> 436 >> >> 1 >> >> 1 >> >> 15 >> >> 2 >> >> .23 >> >> >> >> Can anyone tell me which specs to use and/or explain this compensated >> wavelength issue? >> >> >> >> Thank you, >> >> Tim >> >> KI6VBY >> > Hi Tim, KI6VBY > > Read please the book "REFLECTION" Transmission Lines and Antennas by > M. Walter Maxwell, W2DU Chapter 22 The Quadrifilar Helix Antenna pages > 22-1 to 22-23 and also > "Experimental Investigation of Quadrifilar Helix Antennas for 2400 MHz" The > AMSAT Journal May/June 2004 > In a separate email I have sent to you both articles as an attachement. > > 73" de > > i8CVS Domenico > > > > _______________________________________________ > 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 __________ Information from ESET NOD32 Antivirus, version of virus signature database 4468 (20090929) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com __________ Information from ESET NOD32 Antivirus, version of virus signature database 4471 (20090930) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com _______________________________________________ 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
