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Airborne Varan-S X-band SAR data radiometric analysis

Abstract This paper addresses the radiometric correction and the absolute calibration of the Varan-S X-band SAR slant range images of a scene in the Oltrepo Pavese (Italy) test site. In order to offer a further possibility, as compared with extended targets, a calibration experiment was pursued by deploying thirty trihedral corner reflectors (CR) on that test site. As a first approach, the nominal antenna elevation gain pattern was analytically reproduced, to be used in the radar equation. The CR's responses, with their known radar cross-sections (RCS), were used to determine the scaling factor for each tested image. Then a radiometric correction was applied in the range direction, taking into account the antenna gain and the range dependence. The resulting gamma profiles, from far to near range, are discussed and recommendations for future work are given.