The Finite-difference Time-domain-generalized Boundary Condition Method Efficiently Analyzes Thin-layer Artificial Electromagnetic Structures

In order to be satisfied with the application requirements,sheet has been widely used in practical engineering.The metasurfaces electrically large and subwavelength features lead to huge computational problems.Due to the obvious advantages of Finite difference Time Domain(FDTD)method in analyzing electromagnetic problems and the universality of Generalized Sheet Transition Conditions(GSTCs)compared with traditional boundary conditions,it is of great significance to combine FDTD and GSTCs to analyze the electromagnetic characteristics of sheet structures.In this paper,a method based on the combination of FDTD and GSTCs is proposed to analyze the electromagnetic properties of any broadband sheet by introducing complex conjugate pole residues(CCPR)pairs to vector fitting susceptibilities,and then the method is applied to analyze the scattering properties of graphene The main work of this paper is as follows:Firstly,the basic theory of the combination of two-dimensional FDTD-GSTCs is introduced,and an example of two-dimensional metasurfaces focusing and beam deflection is given.Since three-dimensional problems are mostly analyzed in practical engineering applications,the equivalent model and basic theory of the combination of three-dimensional FDTD-GSTCs is introduced,and some concrete example of three-dimensional metasurfaces model are also given.Secondly,this paper analyzes the influence of graphene conductivity factors and gives a dispersion model of graphene,while observing the regulation of graphene conductivity by external bias electric field.The method based on the combination of FDTD-GSTCs is proposed to analyze the electromagnetic characteristics of any broadband graphene structure by introducing the complex conjugate pole residue(CCPR)pair fitting susceptibilities,which verifies the correctness and efficiency of the method used in this paper.In practical applications,graphene generally doesn't exist independently,because the electromagnetic properties of graphene loaded on thin dielectric plates are analyzed and studied.The tangential field on both sides of the electromagnetic superface is discontinuous,so a magnetic current term will appear.Because the sheet is characterized by electromagnetic polarizability,the sheet is homogenized,which will improve the calculation time and efficiency.