Hi AMSATs,
The Indian Space Research Organisation (ISRO) has
informed me that the best way to work HAMSAT is with
linear antennas.ISRO who made the satellite has designed the HAMSAT with circular up and downlink.
With the use of linear antennas the loss with be always 3dB, even with polarization changes due to faraday rotation.
When the ground station uses circular polarization the
losses will be in the order of 0 to 20dB.
0 dB when polarization is same, and up to 20dB when
polarization changes totally.
When using circular polarization the groundstation need to be able to change between RHCP and LHCP.
Because this is not in the power of most hams, a
linear antenna is a very good option.It will give only a 3dB loss over a more high-tech switcheable station.
With the high level downlink signals, and the
sensitive uplink the 3dB loss should be not a problem
at all.
Klla: amsat