A Study On Antenna Radiation Property Control Based On Near-zero Metamaterials

In the past 20 years,great interests have been focused on artificial electromagnetic metamaterials,which are of optimistic prospects and potential.Analysis and application of electromagnetic metamaterials have been developed rapidly.The anisotropic near-zero metamaterials is a special electromagnetic metamaterials with novel electromagnetic properties such as zero refractive index and zero phase shift.The property of controlling the propagation of electromagnetic wave with near-zero metamaterials can be used in many microwave devices and antennas.This thesis mainly studies antenna radiation property control based on anisotropic near-zero metamaterials.Contents of this thesis include:In chapter 1,the background and significance of the thesis topic have been given.Development and state-of-art of electromagnetic metamaterials have been introduced.In chapter 2,related electromagnetic theory of this thesis is introduced,and it mainly includes two parts: working principle of aperture antennas and near-zero metamaterials.The former part mainly involves the field equivalence principle and aperture radiation mechanism.The latter part includes the effective medium theory,parameter retrieval method,properties of the anisotropic near-zero metamaterials,and metamaterial unit cell design,etc.In chapter 3,aperture radiation property based on anisotropic near-zero metamaterials has been studied.With different metasurface loadings with near-zero property,beamwidth control for the E-plane and H-plane of the aperture antenna has been achieved,and the antenna gain has been significantly increased.In chapter 4,radiation property of a circular patch antenna based on radial anisotropic near-zero metamaterials has been studied.A low profile omni-directional antenna with narrow beamwidth on the vertical plane has been proposed.Due to the finite near-zero bandwidth of the loading metamaterials,beamwidth reduction has been achieved in a certain bandwidth.Finally in chapter 5,the summary of this thesis and some future work considerations have been given.