Electromagnetic Scattering Analysis Of Finite Period Structure

The finite periodic structure is an array structure in which elements are periodically arranged.It is often used in microwave communication fields such as antennas,radars and filters with a wide application prospect.For large-scale finite periodic structures,the traditional methods of full-wave analysis are limited by the computer capability,and it is difficult to quickly obtain the electromagnetic characteristics of the large-scale finite periodic structures.Therefore,it is necessary to delelop efficient numerical methods for analysing the electromagnetic characteristics of finite periodic structures.Method of moments(Mo M),which is relatively mature in dealing with electromagnetic scattering problems,is a classic numerical method in electromagnetic fields.However,the impedance matrix formed from Mo M procedure is a dense matrix.When the number of finite periodic structural elements increases,the amount of calculation and storage will increase in solving the matrix equation with traditional Mo M.In this thesis,specific entire domain basis functions for different structures are employed,which ensure that the basis functions can model the distributions of induced current density on the conductor surfaces greatly and result in reducing the number of unknowns.Furthermore,besed on the characteristic that the impedance matrix of the periodic structure is a multilevel block-Toeplitz(MBT)matrix,the fast Fourier transform(FFT)is used to to deal with the matrix-vector multiplication.Thus,the matrix equation can be quickly solved by iterative mathod such as Generalized Conjugate Residual Method(GCR),and finally the Radar Cross Sction(RCS)of finite periodic structure can be calculated.In this thesis,the entire domain basis functions of conductor strips and crossed dipoles are introduced,the elements of the impedance matrix of Mo M are analyzed,the distributions of induced current density under plane wave excitation are calculated,as well as the RCS of finite periodic structure consist of strips.Hence an approach for fast computing the electromagnetic scattering from a finite periodic structure is implemented.