Highly Squint SAR Data Focusing Using Keystone Transform and Subaperture Processing

In this paper, an algorithm using Keystone transform and subaperture processing is proposed for focusing synthetic aperture radar data in highly squint angle and high resolution. The whole processing of the proposed algorithm consists of two main steps. Firstly, the keystone transform is used to remove the linear range walk to reduce the range-azimuth coupling of the echo signal. Afterwards, the space variant residual range cell migration (RCM) and azimuth modulation are compensated through a subaperture DFT processing, where the corresponding relationship of the Doppler frequency and azimuth angle is utilized. The proposed algorithm can process SAR data under a squint angle 80° and the resolution 0.5m, demonstrated by the experimental results of the simulated data.