Research And Design Of Electromagnetic Polarization Control Structure Based On Metamaterials

Artificial polarization control metasurface is one of the forms of electromagnetic metamaterials.Polarization control metamaterials manipulate the electromagnetic resonance characteristics of metamaterials to realize the polarization control function of electromagnetic waves.Traditional electromagnetic polarization control devices have shortcomings such as high profile,single polarization mode,and low polarization conversion efficiency.The emergence of polarization control metamaterials has just solved these problems and has become a new technological approach to design high-performance polarization control devices.Aiming at the problems of traditional polarized materials,this thesis takes the electromagnetic resonance of electromagnetic waves in anisotropic metamaterials as the research object.This thesis studies the polarization regulation characteristics and physical mechanisms of anisotropic metamaterials,and designs broadband types,Multi-band and reconfigurable polarization manipulated metasurface,respectively.In addition,transmission characteristics of linearly polarized waves are analyzed,and the performance of designed polarization manipulated metasurfaces are verified through experiments.The work and innovations of this dissertation is as follows:Based on the Fabry-Perot resonator,a broadband transmission-type polarization manipulated metasurface is designed.According to the electromagnetic characteristics of metamaterial,the physical mechanism at several resonances and the reason for the high-efficiency polarization conversion are analyzed by using surface current and Stokes theorem.The mathematical method is used to describe the reflection characteristics of electromagnetic waves between metal layers,which provides theoretical guidance for the design of multi-band,broadband and reconfigurable polarization manipulated metasurfaces.A triple-band polarization manipulated metasurface was designed.According to the electromagnetic resonance characteristics of the polarization manipulated metamaterial,an equivalent circuit diagram was established during the analysis process to obtain the relationship model between equivalent circuit parameters,structural parameters and resonance frequency.This design provides a method for the design of multi-band,broadband and reconfigurable metasurfaces.A reconfigurable polarization manipulated metasurface is designed,and the dynamic manipulation of different polarization functions is realized by loading PIN diodes on the surface of the polarization manipulated metasurface.When the diode is in the OFF state,the designed polarization metasurface realizes broadband linear to circular polarization while realizing dual-band cross-polarization in the ON state.Constructing the equivalent circuits of the diode in different states and studying the relationship between the equivalent circuit model and the structural parameters,which provides an analytical method for explaining the physical mechanism of the reconfigurable polarization metasurface.Finally,combining linear to circular polarization metasurface with the linear antenna to obtain a metasurface with antenna loaded.The simulation results show a good axial ratio and standing wave characteristics,which proves circularly polarized waves are effectively radiated.Although electromagnetic waves have small diffraction,they do not have much impact on the performance of the proposed metasurface with antenna loaded.This design plays an important practical application value in microwave communication systems.This dissertation deeply explores the physical mechanism of anisotropic polarization manipulated metamaterials,analyzes designed metasurfaces from different angles,which enriches the design and research system of polarization manipulated metamaterials and can be used as a reference for the design of broadband,multi-band and reconfigurable polarization metasurfaces.