A broadband double‐layer transmissive metasurface (TMS) for effective generate vortex electromagnetic wave is presented in this paper. The proposed TMS consists of two types of elements. The first element is composed of a multi‐resonant dipole and four metal vias. The metal vias increase the coupling strength between the upper and lower layers to improve transmission efficiency. On the basis of the first element, the second element adds stubs to ensure sufficient phase shift. The far‐field cross polarisation is eliminated by special element arrangement. Then, a centre‐fed linear polarisation TMS is designed to generate orbital angular momentum beams with mode l = −1. The proposed TMS is designed, manufactured and measured to verify the proposed design. The measured results indicate that a maximum gain of 20.8 dBi and narrow divergence angle of ±5° are achieved at 18 GHz. Furthermore, mode purity is higher than 86.1% within the 17 to 19 GHz band. The proposed double‐layer TMS saved costs, reduced weight and without assembly error is a good candidate for OAM generator.

中文翻译：

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基于双层透射超表面产生涡旋电磁波的有效方法

本文提出了一种宽带双层透射超表面（TMS），用于有效产生涡旋电磁波。提议的TMS由两种类型的元素组成。第一个元件由一个多谐振偶极子和四个金属通孔组成。金属通孔提高了上层和下层之间的耦合强度，从而提高了传输效率。在第一个元素的基础上，第二个元素添加了短截线以确保足够的相移。特殊元件的布置消除了远场交叉极化。然后，设计了一个中心馈送的线性极化TMS来生成模式为l = −的轨道角动量束1.设计，制造和测量建议的TMS以验证建议的设计。测量结果表明，在18 GHz时可获得20.8 dBi的最大增益和±5°的窄发散角。此外，在17至19 GHz频带内，模式纯度高于86.1％。拟议的双层TMS可以节省成本，减轻重量且没有组装错误，是OAM发生器的理想选择。