Design Of Polarization Modulated Metamaterials And Research On Their Performance

Metamaterial(MM),as an artificial electromagnetic(EM)structure with extraordinary physical phenomenon,has important promising applications in areas such as aviation,aerospace,medical and health.Manipulation of the polarization states of EM waves based on EM resonant characteristics of MM has always been one of the most attractive scientific hot pots.Traditional structural materials with polarization conversion cannot satisfy the requirements for their lagre thickness and single polarization state character.However,appearance of MM provides a new route to design high-performance structure with polarization conversion.Aiming at the exist questions of the traditional polarization-modulated materials,the EM response characteristics in MM are studied.In this dissertation,the polarization mechamisms,asymmetric transmission phenomena and physical mechanism of MMs are proposed by the systematic study.The models of high-efficiency,multi-and broad-band polarization-modulated MMs are presented and verified.By the way,analysis of asymmetric transmission characteristics of linear polarized waves is also illustrated.The theoretical analysis mechanism of polarized modulation-type MMs was established and perfected,and a method of one-way and selective regulation of polarized modulation-type MMs is proposed.The major works of this dissertation are as follows:(1)The equivalent circuit model for polarization modulated MMs is constructed.According to EM response characteristics,the model between effective EM parameters,structural dimensions and resonant frequencies is established.It is obtained that the key to determine polarization states of reflected waves is the different reflected phase,which provides theoretical guidance for the design of multi-band,broadband and multiple polarized MMs.(2)A perfect dual-band reflection-type MMs based on asy mmetric pattern is proposed.Aiming at the present situation of MMs constructing with sy mmetric pattern more,a physical analysis model of multi-stage reflection interference is established using multi-resonant technique.Constraint relationship between polarization states and impedance characteristics is formed,which makes different polarization states of MMs realized.(3)A multi-band and selectable polarization-modulated MM with asy mmetric transmission(AT)effect is presented.In view of the current of the single polarization,based on local EM coupling effect,multi-band polarized control effect is realized through multiple resonance technology.And it satisfies the need for selective regulation of polarization modulated MMs using its features of band-stop and band-pass,which is significant for the application of selectable polarization-controlled MMs in microwave switching devices.(4)A broadband and selective polarization-modulated MM with AT effect is proposed.Constraint condition of AT effect for linearly polarized waves is analyzed.By using the multi-stage polarization coupling and the frequency selective characteristics,the selective transmission and conversion of polarization-modulated MMs for different polarized waves are realized creatively.This method can convert two orthogonal polarized waves in the band of 9.9~12.5 GHz and 16.1~22.5 GHz respectively,and keep the polarization conversion efficiency more than 80%.This research explores the mechanism of polarization control of metamaterials in depth.The generation of multi-stage reflection interference physical model and multi-resonance mechanism develops and enriches the theoretical research system of polarization modulation-type MMs.It has important guiding significance for designing high-efficient,multi-band and broadband polarization modulation-type metamaterial.