Pat:
I think rotating for polarity matching is more important on the downlink. On uplink, more TX power may be simpler/easier as needed. I've wanted a bit more gain than what I get from the 4 or 6 element linear-polarized yagi on 2M. I keep thinking about building a CP cheap-yagi.
The issue with a CP antenna is transport. You might be able to get same effect with 2 linear antennas and appropriate phasing lines and mechanical offset - a lot of the early AO10 and 13 ops went that way.
We had M2 antennas at the AO27 ground station. They are very rugged, well made. However, the assembly method uses insulating plugs and push-nuts (so does my old Hy Gain sat array); they are a PITA to assemble and not meant for disassembly other than separating at boom joints. The 70cm antenna is rugged enough (and much smaller) for transport in sections, the longer 2M elements are succeptible to damage in a CP config. An option for 70cm is to use the bottom half of a longer boom CP antenna; I have been doing this with reasonable success on my home station.
No experience with GA, so can't help there.
FYI, Directive Systems changed owners approx a year or so ago and is now in Virginia. They were at Vienna and I expect they will be at Manassas and Berryville. A pair of 4 or 6 element 2M antennas (maybe their rover special) with phasing lines might make a good CP array. May be worth a call to them.
73 Steve KS1G
On Thu, May 1, 2014 at 6:15 PM, Paul Stoetzer [email protected] wrote:
Pat,
I have only used linear antennas and I can say that I need to constantly make adjustments to my polarity for the best signal. I think I would find it very difficult to operate using a linear yagi on a tripod unless I had enough gain to overcome the polarization fades.
73,
Paul, N8HM
On Thu, May 1, 2014 at 5:13 PM, Pat Kilroy [email protected] wrote:
Hi! Can anyone give me a recommendation for the RHCP antenna types for satellite work by the (new?) Gulf Alpha outfit?
http://www.GulfAlphaAntennas.com/
In particular, do you have first hand experience with the Gulf Alpha portable 2m 3x3 element RHCP on the 4ft boom and the 70cm 5x5 element RHCP on the 3ft boom? Or do you know someone who does?
If I am so lucky, I would also appreciate if there are any comparisons of these types to the two "extremes" of competitors: M2 436CP30 on the one hand and Arrow II (or the new Alaskan Arrow) antennas on the other.
http://m2inc.com/index.php?ax=amateur&pg=106 http://arrowantennas.com/arrowii/146-437.html
In my application of interest, I know the 436CP30 is considered overkill because I am concerned about portable or semi-portable ground stations at the moment, but features such as construction technique and durability can be related among these units.
As an aside, for those of you who use linear Yagi antennas for portable satellite work, how important is it for you to rotate the sense (polarization) of your antennas, vertical through horizontal, during a given contact? Not worth the bother? Or do you think "next time I'm gonna build in a way to rotate the plane of my uplink/downlink antenna"???
Thoughts?
Thank you very much,
Pat Kilroy N8PK
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Via the AMSAT-DC mailing list courtesy of AMSAT-NA [email protected] http://amsat.org/mailman/listinfo/amsat-dc