Research On OAM Waves Utilizing Multifunctional And Mechanically Rotating Phase Shift Metasurface

To solve the problem of spectrum strain,researchers are trying to find ways to expand communication capacity.Orbital angular momentum is used to increase communication speed because there are countless orthogonal modes.In order to generate vortex waves carrying different orbital angular momentum modes,phase-shifted metasurface stands out from many antenna types due to its advantages of easy fabrication,low and plane profile,high gain,and arbitrarily controlling of polarization,phase,amplitude,impedance,etc.of electromagnetic wave,and has become a favored way for researchers to generate vortex waves.In this paper,based on vortex wave generated by phase shift metasurface,three metasurfaces with different functions are designed,which realize vortex wave multiplexing,mode reconfiguration and beam scanning respectively.The main work of this paper is as follows:1.A broadband dual-polarization multi-beam vortex reflective metasurface is designed.Firstly,a wideband dual-polarized reflectarray working at 13-15.5GHz is designed.Its structure consists of four L-type and four parasitic patch type reflective elements,which can realize the independent regulation of 360° phase shift of two orthogonal polarization.Secondly,by calculating the phase compensation of single or multiple vortex beams,a 16×16 element array is formed.Finally,vortex waves with single beam,double beams and four beams of x and y polarization can be generated,realizing the combination of frequency multiplexing,polarization multiplexing,spatial multiplexing and mode multiplexing.2.A 2-bit reconfigurable vortex wave transmissive metasurface with mechanical rotation mode is designed.Firstly,two elements working at 15.5GHz are designed,and the transmissive amplitude and phase are >0.9 360° phase shift and >0.89 300° phase shift respectively.Secondly,based on the phase compensation calculation of spherical wave to plane wave and the proposed reconfigurable phase superposition method of 2-bit mechanical rotation mode,the top plate consisting of the first element array and the middle plate and the bottom plate consisting of the second element array constitute the reconfigurable vortex wave antenna.Finally,the bottom plate is rotated at 0°,90° and 270° respectively,and the reconfigurable vortex waves with high gain and aperture efficiency in modes 0,1,-1 or 0,2,-2 can be obtained.3.A mechanical rotating beam scanning vortex wave transmissive metasurface is designed.Firstly,two units of the second work design are adopted.Secondly,based on the phase compensation calculation of generating different modes and the phase calculation of mechanical rotating beam scanning,the vortex wave antenna of beam scanning is obtained by the top plate consisting of the first unit cell and the middle plate and the bottom plate consisting of the second unit cell.Finally,the vortex beam with high gain and aperture efficiency in different directions can be obtained by rotating the third plate at multiple angles.