Issues in reducing the diffraction of vortex waves: Metasurface structure, physical properties, and algorithm

Vortex waves demonstrate infinite potential for channel capacity expansion. This paper will utilize metasurfaces to conduct a comprehensive optimization study of non-diffracting vortex waves in three key steps. First, traditional square meta-atoms will be reconfigured into hexagonal arrangements to improve density and spatial utilization, thereby increasing the precision of beam steering phase manipulation and initially reducing the divergence of the vortex waves. Next, by applying the generalized Snell's law, spherical vortex waves generated by the horn antenna will be transformed into high-gain vortex waves with reduced diffraction characteristics, facilitating more efficient transmission. Finally, a non-diffracting Bessel wave will be integrated with the vortex wave to enhance its non-diffracting properties while preserving high purity.