针对圆极化波,通过同极化反射超表面结构单元的空间排布,设计实现了一种二维非色散高效相位梯度超表面.同极化反射相位可以通过同极化反射超表面结构单元金属线的面内旋转来自由调控.实现的相位梯度超表面可对左右旋入射波产生相反的相位梯度.当线极化波入射到超表面上时,反射波被分为两束向相反方向传播的圆极化波.仿真了线极化波垂直入射时的反射功率密度谱,仿真结果与理论上设计的异常反射方向一致.制作了厚度为2mm的超表面样品,测试了其镜面反射率曲线.实验结果表明,线极化波垂直入射时,超表面在9.5~19.0GHz的镜面反射率降至-5dB以下.
For dealing with circularly polarized waves, a high-efficient two-dimensional dispersionless phase-gradient meta- surface is devised and achieved by spatially arranging co-polarized reflective metasurface unit cells. The phase of the co-polarized reflection can be freely modulated via a rotating metallic wire of the co-polarized reflective metasurface unit cell in-plane. The achieved phase gradient metasurface can produce opposite-sign phase gradient for left-and right- handed circularly polarized incident waves. During linearly polarized wave incidence, the reflected waves will decompose into two counter-directionally propagating circularly polarized waves. Reflective power density spectra for the linearly polarized wave in normal incidence are simulated, which are well consistent with the theoretically designed anomalous reflection direction. A 2 mm thick sample is fabricated and the mirror reflectivity curve is measured. Experimental results show that for linearly polarized wave normal incidence, the mirror reflectivity is reduced to below -5 dB in a wide band from 9.5 to 17.0 GHz.