A Novel Wavenumber Domain SAR Imaging Algorithm Based on the Fractional Fourier Transform

The conventional Wavenumber domain algorithm (WDA) employs Fast Fourier transform (FFT) to implement matched filter. It is characterized by its high precision SAR imaging. Compared with FFT, Fractional Fourier transform (FrFT) can provide lower and narrower sidelobes when it is applied to compress chirp signals at the optimal transform. This paper proposed a novel SAR imaging algorithm, termed FrWDA which replaces FFT in WDA with FrFT. The FrWDA was derived and its implementation was presented. How to choose the optimal transformation order was given subsequently. The FrWDA preserves high precision focusing, and has better performance on sidelobe suppression. The FrWDA is more suitable for the high precision SAR imaging, especially in target detection and recognition. Simulation results demonstrate that FrWDA provides better performance on focusing and sidelobe suppression compared with the classical FFT-based WDA.