Broadband, High‐Efficiency, and Polarization‐Insensitive Transmissive Microwave Metasurface With Multi‐Layer Hollow Structure for Generating OAM Beams

ABSTRACT Extensive research on metasurfaces has been conducted in recent years. However, most existing metasurfaces, especially those of the transmissive microwave type, suffer from narrow bandwidth, low efficiency, or polarization sensitivity. A novel transmissive microwave metasurface is proposed that achieves broadband, high‐efficiency, and polarization‐insensitive performance. The unit cell features a multi‐layer hollow structure. Simulation results show that the unit cell exhibits a transmittance above 0.7 over the frequency range of 30 to 36 GHz, with a maximum exceeding 0.9. For both left‐handed circularly polarized (LCP) and right‐handed circularly polarized (RCP) incident waves, the unit cell provides full 0 to 2π abrupt phase coverage with consistent phase response, ensuring broadband and polarization‐insensitive operation. To validate the design, an orbital angular momentum (OAM) metasurface is constructed using the proposed unit cells. Simulation results demonstrate that the metasurface can generate four OAM beams with distinct topological charges and deflection directions when subjected to incident waves with arbitrary polarization. This work offers a promising approach for realizing broadband, high‐efficiency, and polarization‐insensitive transmissive microwave metasurfaces, with potential applications in high‐speed wireless communication systems.