Study On Controlling The Radiation Characteristics Of Electromagnetic Wave Based On Holographic Artificial Impedance Surface

Holographic artificial impedance surface(HAIS)is discussed in this thesis that presents a foundation for the related applications of electromagnetic wave radiation,especially controlling the radiation characteristics of electromagnetic waves.After introducing the development process and the research status of HAIS at home and abroad,combined with several design examples,the design method of HAIS is summarized.By pointing out the existing problems of HAIS and its advantages and insufficiency in the electromagnetic field,the potential applications of HAIS in the electromagnetic field are explored from three levels,and the controlling characteristics and general rules of electromagnetic wave are also studied.Thus solid foundations are set up for using HAIS in wireless communications and other fields.Firstly,this thesis starts from the theory of optical holography and explores the working mechanism and implementation method of beam reconfigurable HAIS.In this process,a reconstruction method based on ‘impedance approximation' is proposed for the first time to avoid complex control networks;the problem of main beam splitting is solved by modifying the impedance modulation equations;the reconfigurable mushroom-shaped high-impedance surface is used to control the sidelobes.Based on this,a reconfigurable HAIS at terahertz band with elevation angles of-70°,-60°,-40°,0°,40°,60° and 70° is designed.This study releases two shortcomings of existing HAIS: the sidelobe problem and the complexity of the control network.Thus it demonstrates the function of HAIS in controlling the electromagnetic waves and their advantages in the field of electromagnetic communications.Secondly,in order to further explore the function of HAIS in controlling the electromagnetic waves,a wideband dual-band dual-circularly-polarized HAIS with shared aperture is proposed and implemented,where clockwise and counterclockwise array arrangements are employed to achieve shared aperture left-handed and right-handed circular polarization radiations simultaneously.This study uses the tensor surface to control the electromagnetic wave,analyzes the relationship between the second-order tensor surface impedance components and the electromagnetic field,and then uses the equivalent impedance method to simplify the implementation process.This research effectively solves the problem of ‘beam scanning along the operation frequency' of HAIS,and summarizes the controlling characteristics of electromagnetic waves on the tensor HAIS used to achieve circularly polarized waves,which once again demonstrates the potential applications of HAIS in the electromagnetic field.Finally,for high power applications in practical engineering,a HAIS with millimeter-wave spatial power combining is developed using the spatial power combining method.The controlling characteristics of electromagnetic waves based on multiple-feed HAIS is explored,and the factors affecting power combining are analyzed and optimized.This research presents important reference for exploring further potential applications of HAIS in the electromagnetic field and controlling behavior of electromagnetic waves.