Expediting Back-Projection for Circular SAR Imaging

Circular synthetic aperture radar (CSAR) wins fame for its ability of multi-aspect observation and high-resolution imaging. However, special flight track and severe coupling challenge most imaging methods. To balance image quality and computational efficiency, we propose an expediting back-projection (EBP) for CSAR imaging. EBP works by dividing the full synthetic aperture into subapertures. Each subimage is formed onto the unified polar grid. Based on the relationship between azimuth time and angular wavenumber, EBP fuses subaperture spectrum together and obtains the reconstructed image followed by two-dimensional Fourier transform. Without interpolation-based fusion, EBP can decrease the loss of spectrum. Moreover, EBP retains the advantages of back-projection (BP) algorithm, such as high percision and pefect motion compensation. Experiment based on simulated CSAR data validates the effectiveness of this proposed method.