New Method for Generating Mixed‐Mode OAM Beam With Controllable Energy Proportion by Tensor Holographic Impedance Metasurface

ABSTRACT In this paper, a mixed‐mode Orbital angular momentum (OAM) beam is generated by tensor holographic impedance metasurface (THIMTS). Different from the conventional impedance superposition principle, this paper proposes a new design method to generate the mixed‐OAM modes. As examples, four THIMTSs are designed: (1) Mixed‐OAM mode l = ±1 or ±2 with equal mode energy distribution proportion (same weight). (2) Mixed‐OAM mode l = ±1 with different mode distribution proportion (different weight) 6:4 or 4:6. The proposed method for generating the mixed‐modes can avoid interference between modes, which exists for conventional superposition principle, and the designed THIMTSs have following advantages: high purity (total 98%), a measured peak gain of 21.26 dBi for mixed‐mode l = ±1 with equal mode energy at 27 GHz, and arbitrary mode energy proportion. The proposed design method can be used to design THIMTS, which has great application values in many fields such as advanced wireless communication with encoding anti‐noise performance or multiplexing high capacity, OAM beam long‐range communication, radar detection and imaging.