An efficient and accurate three-dimensional imaging algorithm for forward-looking linear-array sar with constant acceleration based on FrFT

•A realistic 3D geometry configuration of the forward-looking linear array SAR is built.•Efficient chirp scaling algorithm based on FrFT is proposed for the forward looking linear-array SAR 3D imaging.•Thorough algorithm derivation and approximation error analysis are presented.•Numerical simulation illustrates easy implementation and high efficiency of the method. Linear-array synthetic aperture radar can break through the limitations of traditional SAR on 3-D forward looking imaging, which continues to attract the worldwide attention, especially on 3-D topographic mapping and aircraft blind landing. To overcome the large range migration and strong space-variant characteristic caused by the uniformly accelerated SAR platform, a new 3-D fractional chirp scaling algorithm (FrCSA) for forward looking linear-array SAR with constant acceleration is proposed in this paper. Based on the novel geometry configuration and the equivalent hyperbolic signal model, a chirp scaling operation is employed to compensate the range dependent range cell migration (RCM). Meanwhile, the FrFT tool is introduced to achieve much more accurate focusing. The 3-D imaging results of 3 × 3 × 3 array point scatterers indicate that the proposed method can achieve better focusing capabilities, greater peak side-lobe ratio (PSLR) and integrated side-lobe ratio (ISLR) comparing with the traditional CS algorithm based on FFT.