Antenna Polarization Question
I was listening to a couple of guys on FO-29 having a nice chat about satellite antenna polarization. They were trying to figure out what type of polarization FO-29 used. They looked at the picture of FO-29 on the AMSAT web site and decided that it was not circular. Someone told me that it was circular so I started looking for information. Found this page by WD0E which is quite nice.
http://www.amsat.org/amsat-new/information/faqs/pswitch.php
Is there a more current page that contains this type of information.
tnx W9KE Tom Doyle
I run linear polarization, and just live with the fades.
Saves a lot of complexity and headaches!
73, Jim KQ6EA
On 09/15/2012 06:47 PM, Thomas Doyle wrote:
I was listening to a couple of guys on FO-29 having a nice chat about satellite antenna polarization. They were trying to figure out what type of polarization FO-29 used. They looked at the picture of FO-29 on the AMSAT web site and decided that it was not circular. Someone told me that it was circular so I started looking for information. Found this page by WD0E which is quite nice.
http://www.amsat.org/amsat-new/information/faqs/pswitch.php
Is there a more current page that contains this type of information.
tnx W9KE Tom Doyle _______________________________________________ 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
----- Original Message ----- From: "Thomas Doyle" tomdoyle1948@gmail.com To: amsat-bb@amsat.org Sent: Saturday, September 15, 2012 8:47 PM Subject: [amsat-bb] Antenna Polarization Question
I was listening to a couple of guys on FO-29 having a nice chat about satellite antenna polarization. They were trying to figure out what type of polarization FO-29 used. They looked at the picture of FO-29 on the AMSAT web site and decided that it was not circular. Someone told me that it was circular so I started looking for information. Found this page by WD0E which is quite nice.
http://www.amsat.org/amsat-new/information/faqs/pswitch.php
Is there a more current page that contains this type of information.
tnx W9KE Tom Doyle
Hi Tom, W9KE
For the antenna polarization of FO-29 please read belove: ------------------------------------------------------- AMSAT NEWS SERVICE BULLETIN 254.S1 FROM AMSAT HQ SILVER SPRING, MD, September 10, 2012 TO ALL RADIO AMATEURS BID: $WSR-254.S1
FO-29 JAS-2 Catalog number: 24278 Launch Date: August 17, 1996
Mode and Antenna Polarization: V: RHCP U: RHCP -------------------------------------------------------- i8CVS Note:
Following my experience on FO-29 I can add the information belowe:
FO-29 is RHCP circularly polarized both in uplink and downlink and has a fixed sense both up and down, but because of its orbit geometry and motion, continuously good signals through it for an entire pass can only maintained if the antennas ground station sense is switched, RHCP to LHCP and vice versa in 70 cm and 2 meters usually several times and on both uplink and downlink and so polarization switching relays on board of both up and down antennas are recommended.
Read please my articles about polarization switching published on the AMSAT-Journal March/April 2007 and May/June 2007
73" de
i8CVS Domenico
Domenico,
Thanks for the reply. I am slowly building my sat station back to what it was back in the day when I had a pair of KLM antennas with polarization switching. I have recently added a switchable polarization 70 cm antenna to my current station and am amazed at how often during an FO-29 pass it is necessary to change polarization. My memory is not what it should be but I do not remember as much switching being necessary when using AO-10 era sats. Perhaps they were more stable or the pass was so long that it did not seem like it required as much switching.
"In 1911, Albert Abraham Michelson discovered that light reflected from the golden scarab beetle Chrysina resplendens is preferentially left-handed." After reading this I wondered if it is possible to create a reflector for RF that would do something similar to what this tiny insect does without even trying. When I asked how to change the polarization sense of a lindenblad antenna I was going to build the author of the article told me that it was not necessary to switch it because there were so many reflections it would not matter. Perhaps a controlled reflective surface would work.
tnx & 73 W9KE Tom Doyle
On Sat, Sep 15, 2012 at 3:00 PM, i8cvs domenico.i8cvs@tin.it wrote:
----- Original Message ----- From: "Thomas Doyle" tomdoyle1948@gmail.com To: amsat-bb@amsat.org Sent: Saturday, September 15, 2012 8:47 PM Subject: [amsat-bb] Antenna Polarization Question
I was listening to a couple of guys on FO-29 having a nice chat about satellite antenna polarization. They were trying to figure out what type of polarization FO-29 used. They looked at the picture of FO-29 on the AMSAT web site and decided that it was not circular. Someone told me that it was circular so I started looking for information. Found this page by WD0E which is quite nice.
http://www.amsat.org/amsat-new/information/faqs/pswitch.php
Is there a more current page that contains this type of information.
tnx W9KE Tom Doyle
Hi Tom, W9KE
For the antenna polarization of FO-29 please read belove:
AMSAT NEWS SERVICE BULLETIN 254.S1 FROM AMSAT HQ SILVER SPRING, MD, September 10, 2012 TO ALL RADIO AMATEURS BID: $WSR-254.S1
FO-29 JAS-2 Catalog number: 24278 Launch Date: August 17, 1996
Mode and Antenna Polarization: V: RHCP U: RHCP
i8CVS Note:
Following my experience on FO-29 I can add the information belowe:
FO-29 is RHCP circularly polarized both in uplink and downlink and has a fixed sense both up and down, but because of its orbit geometry and motion, continuously good signals through it for an entire pass can only maintained if the antennas ground station sense is switched, RHCP to LHCP and vice versa in 70 cm and 2 meters usually several times and on both uplink and downlink and so polarization switching relays on board of both up and down antennas are recommended.
Read please my articles about polarization switching published on the AMSAT-Journal March/April 2007 and May/June 2007
73" de
i8CVS Domenico
----- Original Message ----- From: "Thomas Doyle" tomdoyle1948@gmail.com To: "i8cvs" domenico.i8cvs@tin.it Cc: "Amsat - BBs" amsat-bb@amsat.org Sent: Saturday, September 15, 2012 10:34 PM Subject: Re: [amsat-bb] Antenna Polarization Question
Domenico,
Thanks for the reply. I am slowly building my sat station back to what it was back in the day when I had a pair of KLM antennas with polarization switching. I have recently added a switchable polarization 70 cm antenna to my current station and am amazed at how often during an FO-29 pass it is necessary to change polarization. My memory is not what it should be but I do not remember as much switching being necessary when using AO-10 era sats. Perhaps they were more stable or the pass was so long that it did not seem like it required as much switching.
< snip >
tnx & 73 W9KE Tom Doyle
Hi Tom, W9KE
Using AO-10 and in general HEO satellites like AO-13 and AO40 switching polarization was less necessary than using LEO satellites because most of the time the satellite antennas were oriented toward the earth with a small squint angle so that the polarization changed very slowly mostly due only to the Faraday polarization rotation when the wave passed through the ionosphere.
BTW the above HEO satellites were spinning over the Z axis generating the so called "spin modulation" wich sounded like WOW.......WOW.........WOW.........WOW
Only the AO40 downlink at 2401 MHz was less affected by the polarization rotation due to Faraday effect and less affected by the spin modulation.
Hope that some time in the future the HEO satellite P3E will be placed in orbit !
73" de
i8CVS Domenico
participants (3)
-
i8cvs -
Jim Jerzycke -
Thomas Doyle