If anyone can point me in the right direction to find this item I would appreciate it. Additionally, if it is something that I could fabricate and there is good info available online, please forward any appropriate links to me.
David,
PA3GUO has described a homebrew switch on his website, http://www.pa3guo.com/ Click on Antennas, then scroll to the Polarity Switch button.
Nick KB1RVT
Nick, The circuit you referred to can be simplified. The two 1/4 wave 75 Ohm coax sections match the two antennas to 50 Ohms. A 1/4 50 ohm line will delay the signal by 90 degrees for circular polarization. The opposite rotation is accomplished by adding of a 1/2 wave 50 ohm section to delay one side by 180 degrees. Further simplification when using crossed Yagi's is to space one Yagi a 1/4 wave behind the other and use only the 1/2 wave section. The end result is to have one antenna lead or lag by 90 degrees for RH or LH rotation. To make this work both antennas must be the same electrically and any feed line after the matching sections must be identical lengths to the antennas. All wavelength calculations use 2952/frequency in MHz times the VP of the coax for a 1/4 wave in inches. Multiply by 2 for 1/2 wave. Experiment and build your own. Amateur radio is learning by doing!
Art, KC6UQH
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Daniel "Nick" Kucij Sent: Thursday, July 29, 2010 9:11 AM To: amsat-bb@amsat.org Subject: [amsat-bb] Re; Homebrew Polarity Switch
If anyone can point me in the right direction to find this item I would appreciate it. Additionally, if it is something that I could fabricate and there is good info available online, please forward any appropriate links to me.
David,
PA3GUO has described a homebrew switch on his website, http://www.pa3guo.com/ Click on Antennas, then scroll to the Polarity Switch button.
Nick KB1RVT
_______________________________________________ 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
__________ Information from ESET NOD32 Antivirus, version of virus signature database 5324 (20100729) __________
The message was checked by ESET NOD32 Antivirus.
__________ Information from ESET NOD32 Antivirus, version of virus signature database 5328 (20100731) __________
The message was checked by ESET NOD32 Antivirus.
Hi Amsat's
For a homebrew polarity switch I suggest to read my article: "Switching Four Polarizations on a 70 cm Crossed Yagi"
Part-1 in AMSAT Journal March/April 2007 Part-2 in AMSAT Journal May/June 2007
The above switching circuit allove to switch 4 polarizations V-H-RHCP and LHCP on a crossed yagi having the elements spaced 1/4 wavelenght over the boom and dimension of the feeding and delay lines can be scaled for 144 MHz or any other band.
If someone is interested on it I can send a zipped pdf file of both the above articles.
73" de
i8CVS Domenico
----- Original Message ----- From: "Art McBride" kc6uqh@cox.net To: "'Nick/KB1RVT'" kb1rvt@amsat.org; amsat-bb@amsat.org Sent: Saturday, July 31, 2010 6:14 PM Subject: [amsat-bb] Re: Re; Homebrew Polarity Switch
Nick, The circuit you referred to can be simplified. The two 1/4 wave 75 Ohm
coax
sections match the two antennas to 50 Ohms. A 1/4 50 ohm line will delay
the
signal by 90 degrees for circular polarization. The opposite rotation is accomplished by adding of a 1/2 wave 50 ohm section to delay one side by
180
degrees. Further simplification when using crossed Yagi's is to space one Yagi a 1/4 wave behind the other and use only the 1/2 wave section. The end result is to have one antenna lead or lag by 90 degrees for RH or
LH
rotation. To make this work both antennas must be the same electrically and any feed line after the matching sections must be identical lengths to the
antennas.
All wavelength calculations use 2952/frequency in MHz times the VP of the coax for a 1/4 wave in inches. Multiply by 2 for 1/2 wave. Experiment and build your own. Amateur radio is learning by doing!
Art, KC6UQH
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Daniel "Nick" Kucij Sent: Thursday, July 29, 2010 9:11 AM To: amsat-bb@amsat.org Subject: [amsat-bb] Re; Homebrew Polarity Switch
If anyone can point me in the right direction to find this item I would appreciate it. Additionally, if it is something that I could fabricate and there is good info available online, please forward any appropriate links to me.
David,
PA3GUO has described a homebrew switch on his website, http://www.pa3guo.com/ Click on Antennas, then scroll to the Polarity Switch button.
Nick KB1RVT
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
__________ Information from ESET NOD32 Antivirus, version of virus
signature
database 5324 (20100729) __________
The message was checked by ESET NOD32 Antivirus.
__________ Information from ESET NOD32 Antivirus, version of virus
signature
database 5328 (20100731) __________
The message was checked by ESET NOD32 Antivirus.
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
participants (3)
-
Art McBride -
Daniel "Nick" Kucij -
i8cvs