[amsat-bb] Does SO-50 Tumble? Was: "Polarization"

[Andrew Glasbrenner]

Most us passive magnetic stabilization and some sort of solar pressure induced spin. They "tumble" crossing the magnetic equator, and wobble elsewhere.

73, Drew KO4MA

> On Jun 2, 2016, at 7:28 PM, Ken Alexander <k.alexander at rogers.com> wrote:
> 
> So far, I am only active on SO-50 and I have to say I’m impressed with the reception quality with my TH-D72A and Arrow antenna.  The Arrow requires only a twist to peak the signal to very good levels.  I’m starting to notice a pattern where certain polarization angles produce the best results at different times during a pass.  It would be interesting if this turned out to be repeatable…and it leads to my next question:  How much (if at all) does SO-50 or any other satellite tumble during its orbit?  I am assuming that the current breed of ham satellites aren’t large enough to house motors or other devices to control their attitude, which makes me think they must tumble somewhat.
> 
> Once again, thank you all for your forbearance as I mine your collective knowledge to bring myself up to speed!
> 
> 73,
> 
> Ken Alexander
> VE3HLS
> 
> 
>> On May 31, 2016, at 1:51 PM, Bob <WB4SON at gmail.com> wrote:
>> 
>> "The antennas I see in the photos of satellites we work are whips. Is the polarization becoming "circularized" as it re-enters earth's atmosphere or something?"
>> 
>> Yep, that is exactly what is happening.  It is called Faraday Rotation, and as the signal from the satellite passes through the ionosphere, all sorts of polarity changes can and do happen. A linear polarized satellite antenna (horizontal or vertical) can appear to be the opposite or somewhere in between.  That's why folks rotate their Arrow or Elk antennas -- trying to match the polarity.
>> 
>> Using a circular polarized antenna helps a bunch -- it doesn't matter what the polarity of the linear satellite antenna happens to be at any moment in time.
>> 
>> But there is no free lunch -- Even a circular polarized antenna might need to be switched from Right Hand Circular Polarization (the default) to LHCP from time to time depending on what nasty thing the ionosphere is doing at any given moment.  Changing the polarity switch might bring a S0 signal up to S5, a 30 dB improvement.  I had that happen to me during a recent ARISS contact.
>> 
>> 73, Bob, WB4SON
>> 
>> 
>> 
>> On Mon, May 30, 2016 at 8:25 PM, Doug Andrews <dougg27 at hotmail.com <mailto:dougg27 at hotmail.com>> wrote:
>> 
>> 
>> I too have wondered about this.
>> I have not had much trouble hitting SO-50 and some success on AO-85 with a 5 watt handhel