We use the M2 polarity switches in the VTGS for both our 70cm and 2m antennas.
In my experience they work very well. I have not conducted any critical analysis of their performance (Axial ratio measurements and the like), but I can say they are sturdy and solid and in the few years we've had them 'on the tower' I have had no problems with defects or failures (no water ingress or anything like that). Anecdotally, I will say that being able to switch polarizations mid-pass has been of huge benefit, and you can definitely see a difference in signal strength (depending on the satellite, its antennas, geometry, etc.).
So generally, I highly recommend the M2 products for this, if you can afford it. I also use the M2 antennas personally, but can't afford the polarization switches for myself for my home setup.
If you are looking for DIY / cheaper alternatives, The ARRL Antenna Handbook has some good 'schemes' for polarization switching. Depending on how you tackle the problem you may need access to either 75 or 100 Ohm coax for the phasing (I recommend www.therfc.com for this, he has all kinds of cable and may even fabricate some phase aligned ones for you if you ask nicely). Most of those schemes require some type of coax relay, but you might be able to find something relatively cheap on ebay. Also, you can find a good article on using Omron PCB relays for RF work here, if you would like to attempt to 'build' a coax relay: https://www.w6pql.com/using_inexpensive_relays.htm.
Hope this helps! Goodluck!
-Zach, KJ4QLP
Research Associate Aerospace Systems Lab Ted & Karyn Hume Center for National Security & Technology Virginia Polytechnic Institute & State University Work Phone: 540-231-4174 Cell Phone: 540-808-6305
On 3/25/2018 9:58 AM, WB8PFZ via AMSAT-BB wrote:
M2 sells a driven element assembly that allows polarity switching for there 435 antennas. Has any one used this product and can comment? Is there a cheaper way to do this? Thanks Mike _______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb