High-Efficiency Microwave Vortex Beam Generation for Arbitrary Polarizations and Multiple OAM Modes Based on Planar Reflectarray

A single-layer planar reflectarray with compact size 3.87λ
₀
× 3.87λ
₀
is proposed to produce vortex beam with high efficiency and good quality in 5.8GHz. The required phase shift in the reflected metasurface is realized by simply adjusting the radius of dual-ring elements. Thanks to the symmetric structure of the proposed unit-cell, the vortex waves operation can be obtained with arbitrary polarization. A set of reflectarrays producing OAM beams with mode l=1, 2, 3, 4 respectively, are designed and verified using full-wave simulations. Furthermore, the reflectarray with mode l=1 is fabricated and measured for experimental verification. The aperture efficiency of the reflectarray reaches to 22.6%, which is superior to homogeneous antennas. Both the simulated and measured results demonstrate the good performance of the proposed reflectarray.