Joint Mode Testing and Characterization of NISAR S-SAR Instrument

ISRO and JPL(NASA) are jointly developing a state-of-theart L&S band SAR, planned to be launched through GSLV in 2025. The NASA-ISRO Synthetic Aperture Radar (NISAR) is a first spaceborne SAR mission which will be capable of imaging the Earth in both L-Band and S-Band of microwave region with 12 days repeatability. It is based on a novel SAR concept called SweepSAR, which will provide wide swath imagery at high spatial resolution of stripmap SAR^[1]. Through NISAR, the international science fraternity will be equipped with a means of unravelling the highly spatial and temporally complex processes including ecosystem disturbances, ice sheet dynamics and natural hazards like earthquakes, tsunamis, volcanoes and landslides. As per joint agreement between both the organisations, ISRO’s responsibility is to develop S-Band SAR, spacecraft bus, launch vehicle and associated launch services while JPL responsibility includes development of L-Band SAR, 12m reflector antenna, GPS receivers, solid state recorders (SSR), high-rate communication subsystem for science data and payload data subsystem. In this paper, joint mode (S-Band + L-Band simultaneous imaging operation) testing and characterization of NISAR S-SAR instrument at JPL, NASA is described. The paper focuses on testing and verification of various interfaces between L-SAR and S-SAR for successful integration of both Radar instruments. Subsequently, extended cable test, assembled mode testing, Cross Band Isolation, joint mode radiation functionality and compatibility test and results from S-SAR perspective is discussed.