电磁超表面在微波和太赫兹波段雷达散射截面缩减中的应用研究进展

电磁超表面由于其独特的电磁特性为调控电磁波提供了有力工具，合适地设计成编码、随机、相位不连续、完美吸收器等超表面，就能够控制电磁波的散射以及反射特性，实现雷达散射截面的缩减。本文综述了不同的电磁超表面利用漫反射或者吸收等特性实现在微波和太赫兹波段雷达散射截面缩减中的应用。分析表明，编码超表面由不同的数字单元组成，其反射相位差在很宽的频段范围内满足恒定的关系，设计特殊的单元序列使入射的电磁波产生非定向散射，更高bit编码超表面更容易灵活调控电磁波;随机超表面通过调节阵元的尺寸实现宽带移相从而将金属目标特征性强的反射峰打散成一个无规律、杂乱的波，产生漫反射;不连续超表面由于相位不连续可使电磁波发生漫反射或者异常反射;吸收器通过合理设计结构尺寸实现吸收电磁波能量来减小反射。因此电磁超表面在雷达隐身、宽带通讯、成像等方面具有重要的应用前景。最后对电磁超表面在雷达散射截面缩减中应用的发展趋势进行了初步探讨，未来将向着宽带、柔性、大角度等方面发展。

Research Progress of Electromagnetic Metasurface Used for Radar Cross Section Reduction in Microwave and Terahertz Wave

Electromagnetic metasurface with many special electromagnetic properties can be utilized to manipulate electromagnetic wave propagation and reflection .If the metasurfaces were designed for coding ,random ,phase discontinuities ,perfect absorber and so on ,they can manipulate the scattering or the reflection of electromagnetic wave and achieve the reduction of the radar cross section(RCS) .This paper mainly presents the recent progress concerning the reduction of RCS using non ‐ directional scattering or the absorption characteristic in microwave and terahertz wave .The analysis results show that coding electromagnetic metasur‐face can disperse the reflection into a variety of direction by designing the specific coding sequences for different elements .The coding metasurface which are composed of different digital elements ,and the reflection phase difference of these digital elements is constant in a wide frequency range ,and higher bit coding metasurface can flexible manipulate electromagnetic wave .The ran‐dom electromagnetic metasurface can achieve broadband phase shifter by adjusting the size parameters of array element ,and can diffuse characteristic by scattering into random wave of the reflection peaks for metal target .Phase discontinuities metasurface can achieve anomalous or diffuse of wave because the phase distribution is not uniform at the surface .The absorber metasurfaces which are designed reasonably with the physical dimensions of the devices can reduce reflection by absorbing electromagnetic wave energy .So ,the electromagnetic metasurfaces have a large potential application for radar stealth ,broadband communica‐tions ,imaging and so on .Finally ,we discussed the future development of RCS reduction by using the electromagnetic metasur ‐face .In order to satisfy the needs of practical application ,the research of metasurface will continue development in broadband , flexible ,large angle and other aspects .