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中国物理学会期刊

一种宽角域散射增强超表面的研究

CSTR: 32037.14.aps.67.20181053

Research of a wide-angle backscattering enhancement metasurface

CSTR: 32037.14.aps.67.20181053
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  • 提出并验证了一种基于超表面相位梯度设计以实现宽角域后向雷达散射截面(radar cross section,RCS)增强的设计思路.宽角域RCS增强超表面包含两个区域,分别设计大小相等方向相反的相位梯度,控制-45和45方向上的入射电磁波沿入射方向返回;电磁波垂直入射时,在一个区域内耦合为表面电磁波,传播至另一区域再次解耦为垂直反射的自由空间波,分别在-45,0,45方向上形成散射峰,实现了在-4545的宽角域范围内的RCS增强.仿真了宽角域RCS增强超表面在电磁波以不同角度入射时的电场分布和单站RCS,测试了加工样品在912 GHz频带内不同频点处的单站RCS,和仿真结果基本一致.结果表明:设计的宽角域RCS增强超表面在912 GHz的宽带频率范围内,在-4545的宽角域范围内对于x和y极化入射波均有良好的RCS增强效果.

     

    To enhance backscattering, corner reflector and Luneburg lens are usually used. They can operate effectively in a broad angle range and also in a quite wide band. However, corner reflector as a typical structure of backscattering enhancement device, has obvious disadvantages in practical application. For example, it is usually made of metal material, which causes it to be too heavy and bulky. Luneburg lens is generally made of dielectric with strong loss and high cost, which is unfavorable for applications. Thus, it is necessary to explore a new way to realize wide-angle backscattering enhancement. In this paper, a phase gradient metasurface with wide-angle radar cross section (RCS) enhancement property is proposed and demonstrated, which consists of two phase gradients with equal magnitude but in opposite directions. Through designing a reflective phase profile along the surface, an equivalent wave vector can be generated, with doubled magnitude but in an opposite direction to the parallel component of the wave vector of the incident wave. At the incidence angles =-45 and 45, electromagnetic (EM) waves are reflected to the directions just opposite to the directions of incident waves. And at incidence angle =0, the incident EM wave is coupled into spoof surface wave and then guided to another region to decouple into a free space wave. These guarantee RCS enhancement property in a related angular domain. The polarization independent Jerusalem cross unit is used to design the phase gradient, and a wide-angle RCS enhancement metasurface is designed. The simulated results indicate that at the designed incidence angles, directions of the reflected waves are all opposite to the directions of incidence waves for both x and y polarized wave. In order to evaluate the RCS enhancement performances, the mono-static RCS of the designed wide-angle RCS enhancement metasurface is measured. Both the simulations and experiments are in good agreement with each other, and show that the designed metasurface obtains tremendous RCS enhancement performances in a wide-angle domain (-45-45) for both x and y polarized wave with frequencies ranging from 9 GHz to 12 GHz.

     

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