A sub-optimal approach for bistatic joint STAP-ISAR

Moving targets appear defocused within SAR images and their detection is challenging especially in the case of ground targets that are embedded in strong ground clutter. STAP methods show optimal results in the clutter and interference suppression when the signal environment is stationary. This improves detection performance and allows for the application of ISAR based techniques which are then used to obtain high resolution images of moving targets. However, in bistatic system geometry, clutter echo returns are not stationary but range dependent. This situation degrades significantly the STAP performance due to the fact that data are not iid. By modeling the dynamic behavior of the beamforming weight, the losses in performance may be recovered at the expense of doubling DoFs and then significantly increasing the computational cost. The aim of this work is to combine bistatic STAP and ISAR techniques to obtain a well focused image of non-cooperative moving targets with a lower computational cost with respect to the classical bistatic STAP technique. Two principal issues will be addressed. First, a clutter model in the bistatic geometry is developed and then a sub-optimal implementation of the Extended Sample Matrix Inversion to clutter mitigation is proposed. Results of the proposed processing applied to simulated data are provided in order to show the effectiveness of the proposed technique.