A Metasurface Design for Generating Wideband CP and LP OAM Vortex Waves

In this paper, a reflecting metasurface for generating the circular polarization (CP) / linear polarization (LP) orbital angular momentum (OAM) beams are designed. The unit cell can convert the linearly polarized incident waves into the circularly polarized reflected ones by adjusting the polarization angles of the linearly polarized feed. Then, based on the proposed 2-bit unit cells and principle of generating OAM beams, a metasurface for generating the CP/LP OAM beams with +1 mode is developed. To verify the performance, the proposed metasurface is fabricated and measured. Both simulated and measured far-field radiation patterns, as well as the near-field phase and amplitude distributions, have confirmed the generation of the OAM beams. Furthermore, the axial ratio (AR) is lower than 3 dB from 10.0 GHz to 12.5 GHz. Thus, generation of the wideband CP/LP OAM beams are validated. The proposed metasurface is expected to enhance the data transmission rate and anti-interference capability in the wireless communication systems.