Research On Graphene-based Electromagnetic Metamaterials

Graphene,a two-dimensional material,has a single layer carbon atom arranged in a honeycomb structure which has become a “star material” in electromagnetic metamaterials because of its unique physical properties.More and more scholars pay attention to this field.Graphene has more unique physical properties,such as extremely high electronic transport,high strength,softness,good light transmission,and thin thickness.The excellent properties of graphene are derived from its conductivity properties.Many applications based on graphene has been designed according to the tunable conductivity of graphene.Electromagnetic metamaterial is a multi-disciplinary interdisciplinary.Electromagnetic metamaterials is composed of subwavelength structural units usually.Electromagnetic waves can be controlled by a certain arrangement of metamaterial unit cell.Although the various designs of absorbers have been proposed,people still pursue more high performance,such as light weight,thin thickness,broad band,high absorption,polarization insensitive characteristic,dynamic adjustable property,and so on.In this thesis,we will study the mechinism of absorber with better performance and propose a broadband tunable,angle insensitive and polarization insensitive graphene-based metamaterial absorber.As a new concept and new method in electromagnetic fields,metasurface has been developed rapidly.As a new way of communication,orbital angular momentum(OAM)shows increasing remarkable performance and attracts the attention of scholars all over the world.With the concept of metasurface and the characteristics of graphene,the graphene-based metasurface array thas been designed to generate OAM vortex waves,which will provide a new idea for the development of wireless communication.Nowadays,the development of electromagnetic materials has provided people new ways to better control electromagnetic waves and improve the theory of electromagnetic fields.The study of graphene will bring about a new technological revolution for the development of electromagnetic metamaterials.The application of electromagnetic metamaterials brings new possibilities.This thesis will focus on the following aspects of graphene:1.Study on properties of graphene.In this part,we will focus on the conductivity of graphene,and study the theory of the graphene conductivity and the electromagnetic parameters of graphene,including the S-parameter,the equivalent dielectric constant,the Drude model and so on.According to the electromagnetic parameters of graphene,the circuit model of graphene is constructed.In addition,we will study the important surface plasma properties of graphene,and obtain the conditions for graphene to support the surface plasma propagation.Based on this property,a Luneberg lens based on graphene is designed.2.Research of absorber based on graphene.This part will synthesize the various characteristics of absorbing materials,and describe in detail the different methods in the design of absorbing materials.With the material properties of graphene,a new absorbing material with high performance and multi-function havs been developed,and the corresponding absorbing mechanism of the structure has bee discussed.3.Generation of wideband tunable OAM vortex waves using graphene metamaterial array.Combining metasurface with graphene characteristics,This part proposed an antenna array to generate the OAM vortex waves with tunable modes.Moreover,the physical mechanism of the proposed structure in the generation of the OAM has been analyzed,and the characteristics of obtained OAM vortex wave has been discussed.