A Circularly Polarized Fabry–Perot Antenna Carrying Orbital Angular Momentum

A circularly polarized Fabry–Perot (FP) antenna with orbital angular momentum (OAM) order l=1 is proposed in this paper. The presented FP antenna is fed by a patch radiator with conical beam operated at TM21 mode which radiates circularly polarized vortex beam. A single-layer complementary partially reflective surface (PRS) with positive slope of reflection phase is used to increase the directivity and decrease the beam divergence angle of the patch radiator. The proposed FP antenna with vortex beam exhibits a peak gain of 12.1 dBi at 5 GHz with a beam divergence angle of 11 degrees, compared with 5 dBi and 35 degrees for the feed, indicating the validity of the proposed design.