Accurate consideration of sensor parameters in the calibration and focusing of F-SAR data

The F-SAR sensor [1], developed and operated by the DLR-HR institute, is the successor to the well-known E-SAR system and provides very high resolution, fully polarimatric SAR data in multiple frequency bands in addition to several special purpose interferometric imaging modes. The high resolution/high bandwidth regime of operation places significant new demands on the SAR processor, both in terms of image formation and in terms of calibration. This paper describes several of the approaches developed to meet these challenges. As a common feature, they are all based on precision measurements of various sensor components, in particular the high resolution 3D antenna patterns and the precise platform attitude information, that allow the processor to effectively model the sensor as a whole and carry out necessary corrections in a systematic manner. The results presented pertain to sensor calibration, where new approaches more than double the radiometric and phase accuracy, as well as image quality for a number of F-SAR's operational frequency bands.