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自旋式飞行器由于运动轨迹复杂,不仅不能精确测量飞行高度,而且从未被用做SAR成像平台。通过研究自旋式飞行器的三维SAR成像新模型,将测高与三维SAR成像相结合,提出了一种基于三维SAR成像的测高新模型。首先分析了自旋式飞行器天线相位中心运动轨迹的特点,将具有三维空间分布的半螺旋线天线运动轨迹等效为面阵天线;然后基于等效面阵,利用模糊函数理论,推导了相应的三维成像模型,从理论上证明了模型的成像可行性并分析其成像性能;最后在成像模型基础上,提出基于三维SAR成像的自旋式飞行器测高新模型,并从成像角度分析影响测高精度的因素。针对等效面阵非均匀分布的特点,采用后向投影(BP)算法仿真验证自旋式飞行器模型下三维成像的可行性和测高模型的有效性。
Due to the complicated trajectories of a spin-on vehicle, not only the flight altitude can not be precisely measured, but it has never been used as a SAR imaging platform. By studying a new model of three-dimensional SAR imaging of a spin-on vehicle and combining the altimeter with three-dimensional SAR imaging, a new altimetry model based on three-dimensional SAR imaging is proposed. First of all, the characteristics of the trajectory of the phase center of the spin-type vehicle antenna are analyzed. The movement trajectory of the semi-helical antenna with three-dimensional spatial distribution is equivalent to the area array antenna. Then, based on the equivalent surface array and the fuzzy function theory, 3D imaging model, the imaging feasibility of the model is theoretically proved and the imaging performance is analyzed. Finally, based on the imaging model, a new height measurement model of the spin-type vehicle based on the three-dimensional SAR imaging is proposed. the elements of. In view of the non-uniform distribution of the equivalent surface area, the feasibility of three-dimensional imaging under spin-ray aircraft model and the validity of the altimeter model are verified by back projection (BP) algorithm.