A BACK PROJECTION ALGORITHM TO FOCUS SYNTHETIC APERTURE RADAR DATA ACQUIRED FROM STRONGLY NON-RECTILINEAR TRAJECTORIES

In this work we devise a Back Projection (BP) strategy for precise focusing of data acquired by Synthetic Aperture Radar (SAR) sensors moving along highly non-rectilinear trajectories. In order to reduce the computational burden typical of each BP procedure, the proposed approach consists of two processing steps. The first one performs, in a computationally efficient fashion, a rough compensation of the effects induced on the received radar echoes by the nonrectilinear shape of the sensor trajectory. The residual effects not compensated through the first step are accommodated, without any approximation, by the second processing step, which splits the synthetic antenna in a number of adjacent sub-arrays with the aim of further improving the computational efficiency of the overall focusing procedure. The algorithm has been tested on a helicopterborne data set collected by a P-band SAR of the Italian Space Agency.