Angular Resolution Enhancement for Multichannel Forward-Looking SAR Imaging Based on Zero-Shot Learning

With multiple channels receiving echoes in azimuth, multichannel synthetic aperture radar (SAR) has the potential of forward-looking imaging. However, its angular resolution, especially the area along the platform flight path, is poor due to the small variation in viewing angle. In this letter, the scheme of angular resolution enhancement for multichannel forward-looking SAR imaging based on zero-shot learning is proposed. In the scheme, the preliminary imaging results are obtained first with the synthetic aperture processing, and then the results are divided into three equal parts in azimuth, namely, left, middle, and right parts, to construct the dataset. Then by incorporating the frequency-domain loss and mixed attention module, the modified CycleGAN is developed to learning the mapping between the middle part (the area with lower resolution) and the left/right parts (the area with higher resolution). Finally, experimental results are illustrated to verify that the proposed scheme can enhance the angular resolution of the middle area to the level of left/right area for the forward-looking images even without ground truths.