Low-Profile and Wideband Bessel Beams Generator with OAM Using Amplitude- and Phase-Controlled Metasurface

This paper presents a high-order Bessel orbital angular momentum (OAM) beams generator using a metasurface (MS) with independent control of cross-polarized amplitude and phase. By adjusting the unit cell parameters and rotating it around the normal axis, the cross-polarized amplitude of incidence covering $0-1$ and corresponding phase variation covering $0-2 \pi$ can be obtained, respectively. To mitigate the feed blockage effect and reduce the profile, a folded topology is employed for the proposed generator. The measured results from the fabricated prototype exhibit excellent agreement with the simulations, demonstrating that our folded topology produces more concentrated vortex beams and stable field distributions compared to conventional OAM beam generators.