Bistatic TerraSAR-X/F-SAR Spaceborne-Airborne SAR Experiment: Description, Data Processing and Results

Abstract

We report about the first X-band spaceborne-airborne bistatic SAR experiment, using the German satellite TerraSAR-X as transmitter and DLR's new airborne radar system F-SAR as receiver. The data were acquired early November 2007. The importance of the experiment is not only due to its pioneering character, but also due to its potential to serve as a test-bed for the validation of non-stationary bistatic acquisition procedures, novel calibration and synchronisation algorithms, and advanced imaging techniques, as required for future non-synchronised bistatic SAR missions. High-resolution bistatic imaging requires in general a perfect synchronisation of the radar systems, which in the present case is achieved by evaluating the range histories of several reference targets. After synchronisation, non-stationary focussing is performed using a bistatic backprojection approach. Benefiting from the flexibility of both acquisition systems, stand-alone TerraSAR-X monostatic as well as interoperated TerraSAR-X/F-SAR bistatic data sets have been recorded; the simultaneous availability of monostatic and bistatic images will help to understand their similarities and differences. As expected, the bistatic image shows a space-variant behaviour in spatial resolution and signal-to-noise ratio; both outperform their monostatic counterparts in almost the complete imaged scene. A detailed comparison between the monostatic and bistatic images is given, illustrating the complementarity of both measurements in terms of available backscattered energy and Doppler information.