Ultra-broadband OAM generator of high-efficiency, high-purity vortex electromagnetic waves based on an ultrathin reflective Pancharatnam-Berry metasurface for the microwave band

In this paper, a new arc-shaped meta-atom like a fishbone controlled by Pancharatnam-Berry (PB) phase is designed for a microwave band, which can yield a high-purity vortex electromagnetic (EM) waves ranged from 10.63 to 26.86 GHz (relative bandwidth of 86.6%) with an efficiency of more than 90%. A single-beam metasurface with m $m$ = +1, -2 and +3 modes is designed, respectively. Finally, a prototype with m $m$ = -2 mode is manufactured in order to prove the feasibility of the designed metasurface. It shows that the experimental results are in good agreement with the ones of the simulation, which verified the excellent performance of the metasurface. The metasurface has a series of edges such as ultra-broadband, high efficiency, high purity and low profile compared to the conventional metasurfaces, which have strong practical applied value and significance for wireless communication.