This letter addresses the problem of changes in target shape and structure during imaging caused by different height structures being focused at the same height in the terahertz (THz) band. A new circular synthetic aperture radar (SAR) imaging algorithm based on the extraction of target structure scattering characteristics is proposed to solve this phenomenon. First, a circular SAR (CSAR) imaging model is established for different heights. The target was imaged at different heights, resulting in a series of image sequences in different heights and azimuth directions. Then, incoherent tracking of the backscattered energy is used to search for effective scattering centers at different heights. The scattering characteristic curves of different structures are obtained based on the effective scattering centers. Finally, the effectiveness of the proposed algorithm is verified by simulation and measured data. The proposed algorithm has accurately focused the target, while also enhancing the details. In addition, the contrast-to-noise ratio (CNR) of the imaging results has been improved by 4.87% compared to traditional algorithms.

中文翻译：

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基于目标结构散射特征提取的太赫兹环形SAR成像算法

这封信解决了成像过程中由于不同高度结构聚焦在太赫兹（THz）频段相同高度而引起的目标形状和结构变化的问题。针对这一现象，提出了一种基于目标结构散射特征提取的圆形合成孔径雷达（SAR）成像算法。首先，建立不同高度的圆形SAR（CSAR）成像模型。目标在不同高度进行成像，从而产生一系列不同高度和方位角方向的图像序列。然后，使用反向散射能量的非相干跟踪来搜索不同高度的有效散射中心。根据有效散射中心得到不同结构的散射特性曲线。最后，通过仿真和实测数据验证了所提算法的有效性。该算法准确地聚焦了目标，同时增强了细节。此外，成像结果的对比度与噪声比（CNR）相比传统算法提高了4.87%。