Research on Azimuth Multi-beam Arc Array SAR Imaging Method

‍ ‍Arc array synthetic aperture radar （SAR） is a new microwave imaging system used for wide-area observation. Unlike linear array SAR， arc array SAR effectively addresses the limitation of a single observation angle inherent in conventional imaging radars， including forward-looking， side-looking， and downward-looking modes. This advancement overcomes the drawbacks of traditional imaging methods， positioning arc array SAR as a technology with wide-ranging application potential. The curved array SAR system is applied to the carrier platform， which can realize the imaging perception of the large field of view and high spatial and temporal resolution of the terrain information around the platform. It has important development potential and application prospects in military reconnaissance， disaster relief， and other fields. Azimuth multi-beam technology is an important technology that can be used to improve the mapping performance of spaceborne SAR systems， including the ability to achieve high resolution and wide coverage. Due to the equiangular sampling of the arc array SAR in the azimuth direction， the azimuth is non-uniformly sampled， and multi-channel reconstruction must be performed before imaging. In this study， we construct the azimuth multi-channel signal model of the multi-beam arc array SAR system， and the imaging simulation is carried out by the traditional multi-channel reconstruction method. The imaging results show false targets. Since the traditional multi-channel reconstruction method is suitable for most linear arrays， by analyzing the mathematical geometric model of the echo slant range， it is deduced that the multi-beam arc array SAR has an additional phase compared with the linear array synthetic aperture radar. Combined with the arc array antenna structure， the additional phase is caused by the sub-aperture angle. Therefore， the phase error in the azimuth multi-channel echo data is caused by the sub-aperture angle of the multi-channel arc array SAR. The traditional multi-channel reconstruction method cannot be directly used in the imaging processing of the arc array SAR. To achieve focused imaging of stationary targets with the Arc array SAR system， we propose an azimuth multi-channel reconstruction method tailored for this synthetic aperture radar system. Before the multi-channel reconstruction and merging， the additional phase between the azimuth channels is compensated to avoid the azimuth under sampling， and then the azimuth multi-channel data is reconstructed according to the multi-channel impulse response of the arc array. Compared with the traditional multi-channel reconstruction method based on linear array azimuth， the multi-channel reconstruction method suitable for multi-channel arc array SAR is used to process the original data. It can significantly suppress false targets and improve the accuracy and resolution of target detection. Finally， the feasibility of the method is verified using simulation experiments.