Metasurface-based broadband orbital angular momentum generator in millimeter wave region

Orbital angular momentum (OAM) is an intrinsic property that all electromagnetic waves can carry. Interesting properties of OAM beams have enabled many novel applications. But broadband OAM generator has rarely been investigated, especially in the millimeter wave frequency band. In this work, a broadband OAM generator applying a metallic reflective metasurface operating from 59 to 70 GHz is designed, simulated, fabricated and measured. Both simulation and experiment results demonstrate that broadband millimeter wave OAM beams with good quality can be reliably launched by the designed metasurface. The proposed broadband OAM generator alleviates malfunctions caused by dispersion and provides new possibilities of multiplexing for millimeter wave communication applications.