Signal Theoretical Aspects of Bistatic SAR

Bistatic SAR uses separated transmitter and receiver flying on different platforms. This configuration is envisaged to achieve benefits like the exploitation of additional information contained in the bistatic reflectivity of targets, reduced vulnerability in military systems or forward looking SAR imaging. The feasibility of the bistatic concept was already demonstrated by experimental investigations. Nevertheless, a closed satisfying theory reaching from signal modelling over the data collection strategies and the analysis of possible imaging performance to the specification of processors for practical use does not yet exist. The reason may be found in the non-standard geometry resulting in radar signals of high complexity. In this paper, we will start from a signal model for a rather general configuration. Since the changing imaging geometry makes it difficult to derive a general processor, we first look over the well known classes of monostatic SAR-processors. Then, the inversion problem is formulated for the bistatic case resulting in the matched filter processor. Emanating from this, two techniques are derived which are locally optimum either for short apertures or for small scenes. Special attention is turned to the transfer of range-migration type algorithms to the bistatic case.