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A two-dimensional frequency domain imaging algorithm for ground-based SFCW-ArcSAR

ArcSAR can observe the surrounding ground objects at 360°, with the advantages of a wide imaging range and constant azimuth angular resolution. In this paper, based on the stepped frequency continuous wave (SFCW), fourth-order Taylor expansion, and the series-inversion method, the accurate phase expression of the two-dimensional (2D) spectrum is derived, and then the 2D frequency domain imaging algorithm (2D-FDA) for ArcSAR is realized. In the simulation part, the imaging results of 2D-FDA are compared with the back projection algorithm (BPA) and Liao’s method which is the reference for 2D-FDA. The simulation results show that the 2D-FDA is more applicable to process the data obtained from the antenna with the beamwidth larger than 70°. The SFCW-ArcSAR system consists of a vector network analyzer (VNA),a rotating platform, two antennas, and a control computer. Then the system is used for the outdoor experiment. The experimental results of the corner reflector show that the point target analysis of 2D-FDA is consistent with those of the BPA and theory. Under the system parameters in the paper, the measured azimuth angular resolution is 0.0177 radian, the peak side lobe ratio (PSLR) in range direction is -12.46 dB, and the range resolution is 0.48 m on the ground range plane. The imaging results of the real scenario processed by BPA and 2D-FDA are consistent, and the ArcSAR image agrees with the optical image of the experimental scene. The effectiveness and correctness of the 2D-FDA are verified by simulation and experiment.