Generation and Focusing of Orbital Angular Momentum Based on Polarized Reflectarray at Microwave Frequency

TL;DR

This paper introduces a new polarized reflectarray design that efficiently generates and focuses microwave orbital angular momentum vortices, with experimental validation at 12 GHz demonstrating improved beam control and transmission efficiency.

Contribution

It presents a novel analytical theory and two fabricated prototypes for generating and focusing OAM beams, advancing microwave OAM wave manipulation techniques.

Findings

Experimental results agree well with simulations.

Focusing reflectarray reduces beam diameter significantly.

Enhanced transmission efficiency of OAM vortex beams.

Abstract

A novel polarized reflectarray is designed, fabricated, and experimentally characterized to show its flexibility and efficiency to control wave generation and focusing of orbital angular momentum (OAM) vortices with desirable OAM modes in the microwave frequency regime. In order to rigorously study the generation and focusing of OAM, a versatile analytical theory is proposed to theoretically study the compensation phase of reflectarray. Two prototypes of microwave reflectarrays are fabricated and experimentally characterized at 12 GHz, one for generation and one for focusing of OAM-carrying beams. Compared with the OAM-generating reflectarray, the reflectarray for focusing OAM vortex can significantly reduce the beam diameter, and this can further improve the transmission efficiency of the OAM vortex beams. We also show that the numerical and experimental results agree very well. The proposed design method and reflectarrays may spur the development of new efficient approaches to generate and focus OAM vortex waves for applications to microwave wireless communications.