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Up and dwnlink polarization of HAMSAT


This morning I received the answer from ISRO about my
question for the uplink polarization, and why they
used LHCP on the downlink.

The uplink of HAMSAT is in RHCP, opposite of the 2m
downlink that is in LHCP.

I was also supprized to hear that the downlink is in
LHCP, as most amateur sats use RHCP.
The reason that ISRO used RHCP and LHCP is to avoid
interaction between the uplink and downlink signals.

By using opposite polarizations the output of the
satellite would less interact on its 70cm input.
Personaly I think the antennas are at such close range
that this will not really help...
At least we know the right polarizations, and the
reason why it is done.

Myself I have fixed RHCP antennas, and actually have
had never any problems with the HAMSAT.

On the other hand the signals are that strong that it
should be no problem, and most of the hams I hear on
HAMSAT are in aligator mode and can use some
polarization attenuation on the uplink :o)

Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
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