Bistatic FMCW SAR Signal Model and Imaging Approach

The bistatic configuration of frequency-modulated continuous wave (FMCW) synthetic aperture radar (SAR) offers considerable capabilities, reliability and flexibility in designing the compact size and low cost remote sensing systems. Furthermore, the spacial separation between transmitter and receiver avoids the antenna isolation problem. A signal model is proposed here to accurately formulate the bistatic slant range history in FMCW SAR configuration, where the motion during the long pulse duration is taken into account. Moreover, based on the preceding model, an optimization approach is presented to deal with the double square root (DSR) term, and thus an accurate FMCW bistatic point target reference spectrum (BPTRS) is derived. The proposed spectrum can not only address the signal characteristics of bistatic FMCW SAR, but also significantly simplify the bistatic FMCW SAR processing, which will really push the applications of FMCW SAR in the remote sensing field. Furthermore, based on the proposed signal model, the application of an improved range-Doppler algorithm (RDA) is further proposed to focus the bistatic FMCW SAR data. Simulation experiments are carried out to verify the accuracy of this novel formulation and highlight the performance of the proposed focusing approach.