提出了一种基于十字变形结构超表面的极化转换器, 在反射模式下获得了高效超宽带的交叉极化反射.在8.4到20.7 GHz频段内交叉极化反射率大于-0.2 dB, 而共极化反射率小于-12 dB, 在谐振频率点处交叉极化反射率大于-0.03 dB, 而共极化反射率达到-60 dB, 即在谐振点处几乎可实现完全的交叉极化转换; 相对带宽达84.5%, 交叉极化的平均转换效率为96.7%; 此外, 利用电路板刻蚀制备了此极化转换器样品, 实验测试其交叉极化反射率在工作频段内大于-1 dB, 而共极化反射率小于-10 dB, 实验结果与模拟结果吻合, 验证了此超表面可以在超宽的频带内实现线极化电磁波的交叉极化转换.本文设计的超宽带极化转换超表面具有转换效率高和几何结构简单的优点, 可被扩展到太赫兹甚至是可见光频段.

A polarization converter that uses metasurfaces composed of cross deformable structure is proposed. Ultrawideband 90° polarization rotation is obtained in the reflective mode. Reflectance of the cross-polarized wave is above -0.2 dB while co-polarization wave is blow -12 dB in range of 8.4-20.7 GHz. The cross-polarized reflectance is greater than -0.03 dB at the resonant frequency points, and the co-polarized reflectance reaches -60 dB. That is, almost complete cross-polarization conversion be achieved at the resonance frequency points. The relative bandwidth is 84.5% with average orthogonal polarization conversion ratio (PCR) of 96.7%. In addition, the metasurface polarization converter is fabricated on FT5880 substrate. The experimental results show that the cross-polarized reflectance is greater than -1 dB in the operating frequency band and the co-polarized reflectivity is less than -10 dB. The experimental results are in good agreement with the simulation results, which verifies that the metasurface can realize the cross-polarization conversion of the linearly polarized electromagnetic wave in the ultra-wide frequency band. The ultrawideband conversion metasurface has the advantages of high conversion efficiency and simple geometric structure. The similar model can be extended to terahertz or even visible light.