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Satellite Communication - Part 4 (CPI)

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Cross Polar Isolation (CPI)

In installation and pointing/peaking antenna, Orthogonal Mode Transducer (OMT) must be set to be as precise as possible to get the best CPI value.

above is picture of OMT Feed assembly include with BUC and LNB

The minimum value for CPI is 30 dB (better will be good) in Linier Polarized Antennas. The reason is for our receive (Rx)-side as not to get interferenced (distrubed) by other (polarity) Down-Link users, therefore our transmit (Tx) shoild as well not interfere other users that operates at 90 deg (Orthogonal) Polarization.

Note : In LH/RH Circular Polarizations, usually CPI of 27dB (=AR of 1.09) is acceptable enough.


picture above is careless/miss-aligned OMT setting
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