First measurement results of a new highly-accurate active SAR calibration target

The requirements on new spaceborne synthetic aperture radar (SAR) missions are always pushed towards better image quality with respect to signal-to-noise ratio, radiometric accuracy, and spatial resolution. An accurate radiometric calibration of the whole SAR system is crucial to cope with the demand on high image quality. Among other factors, the quality of the calibration depends on the utilized reference targets. Also permanent system monitoring, onboard and by reference targets, is required to guaranty the image quality over the whole mission time. In this paper a new highly-accurate active calibration target (transponder) is presented. The device is currently under development in the DLR-project “Kalibri” [1] and features remote control and alignment as well as an improved internal calibration for stable operation. Furthermore, first representative measurement results could be achieved by acquiring TerraSAR X images.