Improvement of non-linear chirp-scaling algorithm for highly squint bistatic SAR data focusing

Abstract

Bistatic synthetic aperture radar (SAR) has specific advantages, e.g. weak targets detecting, reducing system vulnerability, and anti-interference with low cost and flexible working modes. However, great challenges exist in data processing procedure due to its complicated geometry and 2-D spatial variance, which become more serious when the squint angle increases. Here, an improved non-linear chirp scaling method is proposed to handle highly squint bistatic SAR data. On one hand, Keystone transform is first performed, then linear range walk is removed to deduce the residual range cell migration correction factor, which is used for range compression and removing cross-coupling terms. On the other hand, frequency modulation rates and high-order phase based on the transmitter range offset (RO) and receiver RO are derived according to the geometric configuration. Simulation results show the effectiveness of the proposed algorithm.