Abstract:

In the spaceborne bistatic synthetic aperture radar (BiSAR) system with a geosynchronous (GEO) illuminator and a low-earth-orbit (LEO) receiver, due to the long signal propagation time and high receiver velocity, the slant range error caused by “Stop-and-Go” assumption cannot be neglected. In addition, the spatial-variant characteristics of the echo signal caused by the complex bistatic configuration need to be considered. In this paper, an improved Chirp Scaling (CS) algorithm based on the time-domain perturbation is proposed. First, the signal model is derived based on the geometry. Then, the perturbation functions for correcting the spatial-variant characteristics are presented. Last, the phase compensation functions are generated to enhance the capability of the algorithm. Simulated data results show the validity of the presented method. The algorithm proposed in this paper is able to implement wide-swath and high-resolution imaging and produce the phase-preserved SAR image.

Key words: geosynchronous earth orbit, bistatic synthetic aperture radar, time-domain perturbation, chirp scaling