SAR data processing at high squint

In this paper, an extended step transform algorithm (EST) that is capable of focusing SAR data at extremely high squint angles is presented. To avoid the large walk that is inherent in high squint data, the EST algorithm removes this linear term in its envelope by taking data along the linear range term line. However, by doing this, targets of different ranges may fall onto the same range cell. To solve the range focus problem, a reference function of varying chirp rate to deramp the input signal is used to accommodate the change in the azimuth chirp rate along each range cell. Suitable phase compensation is also necessary to correct for the residual phase error. The EST has been implemented on a SUN workstation and used to process simulated data. The results of the simulations at 55 degrees squint angle are presented