Non-Staggered Hexagonal Meta-Atom-Based Metasurface for Broadband and Multipolarized OAM Generation

To address the limitations of narrow bandwidth, single-frequency operation, and single-polarization in existing vortex beam generation, a compact single-layer reflective metasurface based on a non-staggered hexagonal meta-atom is proposed. The meta-atom integrates a quasi-static hexagonal circularly polarized subunit, a customized linearly polarized subunit and an isolation ring within a compact structure, enabling the efficient broadband multipolarized generation of multiple mode orbital angular momentum (OAM) beam in radio frequency domain. The simulated results show that the designed metasurface can generate OAM beams with different modes <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">l</i> = 1, -2. The far-field measurement results of the vortex beam generated by the fabricated metasurface prototype are demonstrated. The gain of the vortex beam is better than 10 dBi within the bandwidth across 6-20 GHz, and is about 22.1 dBi at 14 GHz. Stable multipolarization performance is achieved across multiple frequency band under circularly polarized, x-polarized and y-polarized excitation, respectively. The proposed design provides a compact and scalable solution for the OAM-based wireless communication.