[amsat-bb] Re: STRaND1 polarity shift observation

Alan wa4sca at gmail.com
Mon Mar 4 11:28:24 PST 2013


To add to what others have said, real CP antennas are not really circular.
They are elliptical, due to slight differences in the lengths of the phasing
harnesses, lack of isolation between the two sets of elements, etc.  That
means, even for a perfect linear antenna, directly on the axis, that if you
rotate it there will be preferred directions.  As you get further from the
axis, the ellipticity becomes more pronounced.  Throw in the fact that the
spacecraft antennas may not, due to interactions, be perfectly linear, and
it is not unexpected to see what you are reporting.  A helix antenna, while
not switchable, will be more nearly CP but will normally have a slight



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