Li Haisheng, An Junshe, Jiang Xiujie
Key Laboratory of Electronics and Information Technology for Space Systems, National Space Science Center, Chinese Academy of Sciences, Beijing 100190, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Sensors (Basel). 2024 May 14;24(10):3119. doi: 10.3390/s24103119.
Spaceborne synthetic aperture radar (SAR) is an advanced microwave imaging technology that provides all-weather and all-day target information. However, as spaceborne SAR resolution improves, traditional echo signal models based on airborne SAR design become inadequate due to the curved orbit, Earth rotation, and increased propagation distance. In this study, we propose an accurate range model for high-resolution spaceborne SAR by analyzing motion trajectory and Doppler parameters from the perspective of the space geometry of spaceborne SAR. We evaluate the accuracy of existing range models and propose an advanced equivalent squint range model (AESRM) that accurately fits the actual range history and compensates for high-order term errors by introducing third-order and fourth-order error terms while maintaining the simplicity of the traditional model. The proposed AESRM's concise two-dimensional frequency spectrum form facilitates the design of imaging algorithms. Point target simulations confirm the effectiveness of the proposed AESRM, demonstrating significant improvements in fitting accuracy for range histories characterized by nonlinear trajectories. The developed AESRM provides a robust foundation for designing imaging algorithms and enables higher resolution and more accurate radar imaging.
星载合成孔径雷达（SAR）是一种先进的微波成像技术，可提供全天候和全天时的目标信息。然而，随着星载SAR分辨率的提高，由于轨道弯曲、地球自转以及传播距离增加，基于机载SAR设计的传统回波信号模型已不再适用。在本研究中，我们从星载SAR的空间几何角度分析运动轨迹和多普勒参数，提出了一种用于高分辨率星载SAR的精确距离模型。我们评估了现有距离模型的准确性，并提出了一种先进的等效斜视距离模型（AESRM），该模型在保持传统模型简单性的同时，通过引入三阶和四阶误差项来精确拟合实际距离历程并补偿高阶项误差。所提出的AESRM简洁的二维频谱形式便于成像算法的设计。点目标仿真证实了所提出的AESRM的有效性，表明对于具有非线性轨迹的距离历程，拟合精度有显著提高。所开发的AESRM为成像算法的设计提供了坚实的基础，并能够实现更高分辨率和更精确的雷达成像。
