Improved fast ETF algorithm for airborne squint SAR imaging

According to the airborne squint SAR (Synthetic Aperture Radar) imaging mode, the exact focusing function for arbitrary scene position is evoluted in details and then an improved fast ETF (Exact Transfer Function) algorithm is further proposed in this paper. Because the evolution is based on exact motion model and exact reference range model, as well as precise computing instead of approximate truncation for azimuth phase preservation, the algorithm performs distinguished phase precision. The algorithm requires no interpolation processing and no linear FM signal constraint, so that it has fine imaging precision and applicability. Meanwhile the algorithm can be easily incorporated into processors using conventional algorithms, blocks and parallel processing compensated varying Doppler centroid complexity and accelerate the processing. Results for processing simulated point targets show the validity of the algorithm.