Research Of Electromagnetic Properties Of Multilayer Graphene And Substrate In Terahertz Band

The terahertz wave,located between microwave and visible light,has important theoretical and practical value in the field of high-speed,large-capacity,high-security and confidential space communication.As a new type of nanomaterial,graphene has unique electromagnetic and optical and properties.Although the terahertz conductivity of single-layer graphene is adjustable,the stacking of multilayer graphene or the addition of a substrate can expand the application of graphene in the terahertz band and increase the degree of freedom of design.In this dissertation,the three conductivity patterns of single-layer graphene in the terahertz band are compared,and the applicable range of different forms of graphene conductivity is analyzed.The Kubo formula is utilized to analyze the conductivity form of multilayer graphene.The theoreticl analysis shows that the random stacking multi-layer graphene can be regarded as the superposition of uncoupled single-layer graphene approximatively.Using the vector fitting method,the surface conductivity and impedance of the multilayer graphene frequency domain are expanded into a rational fractional form,which can be leveraged to solve the convolution of the time domain surface impedance and electric current and the convolution of time domain surface conductivity and magnetic current.The time domain integral equation is established on the surface of multi-layer graphene.The space test and time test are employed to establish the matrix equation and analyze the electromagnetic properties of the multilayer graphene in the terahertz band.The transmission coefficients of graphene in different layers are calculated.Based on the above research,the marching-on-in-degree time domain integral equation method is exploited to analyze the electromagnetics of the multilayer graphene and the ZnO substrate in the terahertz band.The characteristics of a stable electric current and magnetic current are obtained and the radar cross section and the extinction cross section are derived.The comparison of the theoretical results and commercial software simulation verifies the accuracy of the proposed method.