全极化前视SAR三维精细成像技术研究

As filling the “visualization gap” of conventional SAR with respect to the direction in front of radar movement and having the ability of three-dimensional imaging with one flight pass, the forward-looking SAR is expected to be comprehensively used in civil and military applications. However, as an emerging imaging mechanism, there are still several problems that have not yet been solved satisfactorily. Based on this background, this project is dedicated to the study on fully polarimetric three-dimensional fine imaging technique of forward-looking SAR. Firstly, study on accurate modeling of fully polarimetric three-dimensional imaging will be carried out. During this study, “polarimetric-spatial-frequency” joint scattering model of single and unresolved targets and fully polarimetric three-dimensional superresolution imaging model of forward-looking SAR will be established；Secondly, study on fully polarimetric three-dimensional fine imaging methods of forward-looking SAR will be carried out. During this study, advanced signal processing techniques will be utilized and the joint advantages of superresolution, fully polarimetric processing and three-dimensional imaging will be exploited in order to acquire detailed target images. Thirdly, study on precise motion compensation methods of forward-looking SAR will be carried out in order to compensate the imaging error introduced by high speed and great acceleration of platform. Finally, imaging experiments of fully polarimetric three-dimensional forward-looking SAR will be carried out and the measured data will be used for algorithms validation. The achievements of this study will be valuable for establishing the fully polarimetric three-dimensional fine imaging theory of forward-looking SAR and for motivating the application of forward-looking SAR in areas such as military reconnaissance and aviation safety.

由于填补了常规SAR在运动方向前方场景的成像“盲区”，且具有单航过三维成像能力，前视SAR在民用和军用领域均有广泛应用前景。然而，作为一种新兴的成像体制，前视SAR还存在很多问题亟待解决。基于该背景，本项目开展了全极化前视SAR三维精细成像技术研究。首先，开展全极化前视SAR三维成像精确建模研究，建立单个/紧邻目标“极化-空-频”联合域散射模型和全极化前视SAR三维超分辨成像模型；第二，开展全极化前视SAR三维精细成像方法研究，结合先进信号处理手段，挖掘超分辨、全极化、三维成像的联合优势，获取更精细的目标图像。第三，开展全极化前视SAR三维成像精准运动补偿方法研究，修正平台高速度、大过载运动引起的成像误差。最后，开展全极化前视SAR三维成像实验，用实测数据对算法进行验证。项目研究成果对构建全极化前视SAR三维精细成像理论体系，推动前视SAR在军事侦察、航空安全等领域的应用具有重要意义。

由于填补了常规SAR在运动方向前方场景的成像“盲区”，且具有单航过三维成像能力，前视SAR在民用和军用领域均有广泛应用前景。然而，作为一种新兴的成像体制，前视SAR还存在很多问题亟待解决。基于该背景，本项目开展了全极化前视SAR三维精细成像技术研究。首先，开展全极化前视SAR三维成像精确建模研究，建立了典型结构的三维电磁散射模型并分析了其极化响应；提出了保极化角域的概念，建立了单个/紧邻目标“极化-空-频”联合域散射模型；第二，开展全极化前视SAR三维精细成像方法研究，提出了基于Levenberg-Marquardt（LM）的单脉冲前视超分辨成像算法、基于贝叶斯优化的极化单脉冲前视超分辨成像算法、基于极化特征的三维结构参数反演算法，实现了三维超分辨成像和车辆等目标参数的准确提取。第三，开展全极化前视SAR三维成像精准运动补偿方法研究，提出了基于位置估计精度CRLB的非均匀子孔径划分运动补偿方法，克服了平台非规则运动轨迹对成像的影响；提出了基于数据插值的三维稀疏成像运动补偿方法，修正了高速度、大过载、非均匀轨迹等对于成像的影响。仿真和实测数据均验证了算法的有效性。项目研究成果对构建全极化前视SAR三维精细成像理论体系，推动前视SAR在军事侦察、航空安全等领域的应用具有重要意义。