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摘要: 涡旋电磁波,因携带有轨道角动量(OAM),从而具有螺旋状的波前结构。相比于平面波,涡旋电磁波在进行雷达成像时,回波信号中将包含有目标的方位向信息,所以这种电磁波在雷达探测和成像领域中展现出了巨大的应用潜力,有望成为新体制雷达的发展方向。该文主要介绍近年来涡旋雷达成像技术的研究进展,首先介绍了涡旋电磁波的特征和使用均匀圆形阵列进行雷达成像的原理,然后按照涡旋雷达成像模型、涡旋雷达凝视成像算法和涡旋雷达运动成像3种研究方向综述了涡旋雷达成像技术的发展历程和研究现状。最后,对涡旋电磁波在雷达成像中的发展前景进行了展望,并指出未来涡旋雷达成像发展的一些关键的科学问题和趋势。Abstract: Vortex electromagnetic wave carries the Orbital Angular Momentum (OAM), and thus has a spiral wavefront structure, which contains the azimuthal information of the target in the echo signal when performing radar imaging compared with planar waves. Hence, this kind of electromagnetic wave shows great potential for various applications in the field of radar detection and imaging, and it is expected to become the development direction of new-system radars. This paper describes in detail the research progress in vortex radar imaging technology in recent years. First, the characteristics of the vortex electromagnetic wave and the principles of imaging using a uniform circular array are introduced. Then the paper reviews the developmental history and research status of vortex radar imaging technology, according to three research directions: vortex radar imaging model, vortex radar gaze imaging algorithm, and vortex radar motion imaging. Finally, the prospects for the development of vortex radar imaging have been presented, along with the key scientific issues and trends for the future developments of vortex radar imaging.
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表 1 已报道的涡旋雷达成像模型的性能
Table 1. Performance of reported vortex radar imaging models
文献 成像模型 时间(年) 电磁波的发送形式 电磁波的接收形式 达到最大分辨率需要
发送电磁波的次数方位向分辨
率$ {\rho }_{\varphi } $ (rad)文献[60] MIMO 2013 UCA发送整数阶的OAM态为
α的涡旋电磁波UCA使用α整数阶OAM接收 N ${\rm{\pi } }/N$ 文献[64] 2020 UCA发送整数阶的OAM态为
α的涡旋电磁波UCA使用β整数阶OAM接收 N 文献[32] MISO 2014 UCA发送整数阶的OAM态为
α的涡旋电磁波单个天线接收 N $2{\rm{\pi } }/N$ 文献[33] 2020 UCA发送整数阶的OAM态为
±α的涡旋电磁波单个天线接收 $ (N+1)/2 $ 文献[35] 2021 UCA发送间隔为Δα分数阶的
涡旋电磁波单个天线接收 $ N/\Delta \alpha $ 文献[34] SIMO 2018 单个天线发送平面波 UCA使用α整数阶OAM接收 1 $2{\rm{\pi } }/N$ -
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