SAR TRiM Level Radiated Output Verification at Compact Antenna Test Facility

One of the widely used Synthetic Aperture Radar (SAR) antenna configuration is Transmit Receive Integrated Module (TRiM) based 2-D phased array antennas. As the number of TRiM’s per antenna runs into hundreds & higher design margins, failure of few TRiM’s won’t be easily detectable in a spacecraft level beam characterization. Even though internal Calibration (CAL) operations exist to point out TRiM failures, passive elements beyond the TRiM output CAL coupler till the final radiating element are not getting verified neither via internal CAL nor by antenna level beam measurements. This paper proposes a new measurement method for individual TRiM power output verification inside a Compact Antenna Test Facility (CATF) at integrated spacecraft level. Considering various measurement uncertainty factors, expected mean & tolerance levels are calculated for SAR Spacecraft of Indian Space Research Organisation (ISRO). Spacecraft level CATF results are in line with predicted values within tolerance.