Calibration of an X-band airborne synthetic aperture radar with active radar calibrators and corner reflectors

Communications Research Laboratory (CRL) and National Space Development Agency of Japan (NASDA) developed an airborne imaging radar system consisting of an X-band (polarimetric/interferometric) SAR and an L-band (polarimetric) SAR, to acquire SAR data for the research of monitoring earth environments and disasters surveillance. To obtain normalized radar cross-section (sigma-0) of earth surfaces from the data precisely, CRL and NASDA are making external calibrations of the SAR's using calibration reflectors. This paper describes the X-band SAR calibration using corner reflectors (CR) and active radar calibrators (ARC). CR of a triangle trihedral is used fbr radiometric calibration of like-polarization (HH and VV) and to estimate imbalance between HH and VV components. ARC that can select polarization (H or V) in reception and transmission is used fbr calibration of cross-polarization (HV and VH) components. We made a calibration experiment in October 1998 deploying those reflectors in the Tottori dune, Japan. Preliminary results of the experiment are presented, including CR responses when SAR signals were, unexpectedly, saturated.