A reflective metasurface for generating dual-mode dual-polarized high-order Bessel vortex beams with equal divergence angle

A single-layer reflective metasurface is proposed in this study to generate dual-mode dual-polarized high-order Bessel vortex beams with equal divergence angle in Ka-band. The metasurface consists of two different subwavelength elements with different polarisations, which are located in the inner disk region and the outer ring region respectively. The inner element, composed of a square ring and a regular octagon, is proposed to achieve a phase response of 360 degrees. The outer element, which consists of a microstrip line and a double W-shaped line, is designed to achieve the phase compensation and polarization conversion simultaneously. Equal divergence angle of different orbital angular momentum (OAM) modes is achieved by theoretically calculating the radii of the inner and outer regions. The metasurface prototype is fabricated and tested at 29 GHz, and the results show that the high-order Bessel beams with +1 mode of x-polarization and +2 mode of y-polarization are successfully generated. This work provides a simple and practical method to generate dual-mode dual-polarized high-order Bessel vortex beams for high-capacity OAM communications.

Automated summary

This study proposes a single-layer reflective metasurface for generating dual-mode dual-polarized high-order Bessel vortex beams in Ka-band. The metasurface consists of two different subwavelength elements and achieves equal divergence angles of different OAM modes by calculating the radii of the inner and outer regions.