Exactly. Adding, the ability to "flip" your antennas is more than just the rotor and software. Be sure that your feed lines are suitably arranged so as not to get snagged on anything when the antennas go through their full arc, at any azimuth. It can be harder than it looks, but definitely worth it. The nearly minute-long outage as the antenna swings back around has cost me more than a couple of lost QSOs, missed packets, and half-received SSTV pictures.
As Douglas says, flipping an antenna doesn't change the polarization. Circular is still circular; a circle has no orientation. A CP antenna will work the same when mounted X as +, in theory. But in practice, the phycial mounting of the antennas on the cross arm can be a factor, as the cross-arm runs through the RF field of the antanna, and can affect the resulting radiation pattern. If the cross-arm is conductive (steel), use the X orientation; if it's non-metalic (fiberglass), you can use either orientation. My cross-arm is wooden, but I still use the X orientation. Seemed to look better that way :) All that said, I see that the Leo-Pack antennas are end-mounted in their pictures. If your mounting is that way, then it shouldn't matter which oritentation you use.
It is not uncommon for a satellite's perceived polarization to flip as it goes through its pass. I expect this is what you are experiencing when the antenna finally gets back around to track the satellite. Running flipped will help with the minute outage, but you'll still find some passes where the satellite drops out from time to time. So even if all of the satellites you are interested in are RHCP, it's still helpful to have a polarization switch on the antenna to pick up a LHCP signal. If M2 has a polarization switch option, you might try that.
Finally, having the ability to pick up both polarizations isn't going to fix everything. Sometimes a satellite tumbles slowly into an orientation where it's signal just isn't headed your direction. No antenna, especially those on spacecraft, are truly omnidirectional.
Good luck!
Greg KO6TH
Douglas Phelps wrote:
I am sure others will chime in if I am wrong: Flipping the antenna upside down does not change the circular polarization. The following example will explain the advantage of allowing the EL to move 180 degrees: If your Azimuth rotor stops at North, and the satellite will pass from west of north to southeast, at the 360 degree point, the rotor has to stop tracking and move 360 degrees and reacquire the satellite. If, on the other hand, you allow the rotors to move 180 degrees, then the control program will flip the antennas and then will add 180 degrees to the azimuth. Now, when the satellite moves from west of North to east of South, the rotor can track the satellite continuously because in reality the rotor is rotating through South and does not have to stop and rotate 90 degrees.
From: Steve Nordahl via AMSAT-BB <[email protected]>To: "[email protected]" [email protected] Sent: Monday, February 15, 2016 8:00 AM Subject: [amsat-bb] Should I "Flip or Not Flip" my m2 Leo_Pack
I have a lingering question. I installed my recently purchased m2 Leo-Pack per spec. Both antennas are RH per the instructions.I'm very pleased with the performance. However... I have the system installed using a Yaseu G5500 and Green Heron AZ/EL controller. I have the system defaulted and restricted to 90 degrees vertical. I already know this AZ/EL can do the entire flip but have not done so. Satellite reception limitations are driving me to ask this question.. Right now many of the sats I'm able to work in the current RH configuration and only going 90 degrees then doing a AZ to get back on it are good until they pass by me. Once the AZ rotation is completed then I have trouble getting back in or even hearing them. It appears I've fallen out of the correct orientation. Would allowing the flip and having the antennas go upside down be OK? I believe this would make them LH at that point. Does anyone else do this? Is the Leo-Pack the exception for the flip rule? (If one exists) Also, on the Leo-Pack system, I've seen images of others who have angled the antennas x instead of the default + orientation. Take?? What have others observed in performance by changing the angles? Let me know. Steve NS3L FN20hq _______________________________________________ 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
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