复合相位调控的单层双功能反射型超表面

基于传输相位与Pancharatnam-Berry（PB）相位的复合相位调控机制，采用单层介质结构，提出了一种单一圆极化（circularly polarized, CP）波入射和在反射的正交双极化信道条件下实现两种独立功能的双功能超表面。推导分析了传输相位与PB相位对同极化与交叉极化反射分量的相位调控机理，并提出了实现同时调控两种分量的单元设计要求。针对单元旋转造成的PB相位失真，提出了一种加载空心圆形贴片的单元改进模型，确保了相位的稳定性。通过精确调控两极化分量的波束空间相位分布，在单圆极化电磁波入射条件下，该超表面可利用两正交极化信道同时实现两种不同功能。仿真和测试结果表明，在右旋圆极化（right handed circularly polarized,RHCP）电磁波入射下，在13~15 GHz工作频段内，所设计的双功能超表面可在同极化反射信道获得携带轨道角动量（orbital angular momentum,OAM）的偏折涡旋波束，在交叉极化反射信道获得偏折笔形波束。该设计具有结构简单、加工成本低等优点，为实现圆极化信道复用与多功能集成提供了新的思路。

Single-Layer Bifunctional Reflective Metasurface Based on Modulation of Combined Phases

Based on the combination of propagation and Pancharatnam-Berry (PB) phases, a single-layer dielectric structure bifunctional reflective metasurface is proposed to realize two independent functionalities in the orthogonal polarized reflection channels under the condition of single circularly polarized (CP) electromagnetic wave incidence. Firstly, the phase modulation mechanisms of the propagation and PB phases for the co-polarized and cross-polarized reflection components are derived and analyzed, and the design requirements of meta-atom to realize the simultaneous modulation of the two components are proposed. Then, an improved model with a hollow circular patch is proposed to ensure phase stability of the PB phase distortion caused by atom rotation. Finally, by precisely modulating the spatial phase distribution of the two polarized components, the designed metasurface can simultaneously realize two different functions in two orthogonal polarized channels under the single CP electromagnetic wave incidence. The simulation and experimentally measured results show that under the incidence of right handed circularly polarized (RHCP) electromagnetic wave, the designed bifunctional metasurface can obtain the deflected vortex carrying orbital angular momentum (OAM) in the co-polarized reflective channel and the deflected beam in the cross-polarized in the operating band of 13-15 GHz. With the advantages of a simple structure and low processing cost, the proposed design provides a new idea for realizing CP channel multiplexing and multifunctional integration.