Research On Electromagnetic Simulation Method And Application Of Composite Object With Periodic Structures

Periodic structures usually have some special properties,so they play a very important role in the design of microwave circuits and antennas,such as phased-array antenna,frequency selective surface,photonic band gap,electromagnetic band gap,and so on.Because there are not isolated periodic structures in the practical applications,it is necessary to consider the coupling between the periodic structures and other objects in the near field.Adopting the traditional electromagnetic simulation methods,the composite structures combined by periodic structures and other objects are treated as a whole unity,which results in a great number of unknowns in the full-wave analysis.Therefore,it is particularly important to develop the corresponding efficient algorithms.Aimed at the above the issues,the electromagnetic scattering analysis of the composite structures combined by periodic structures and other objects is researched and a new aggregate basis function method is proposed in this dissertation.The work of this dissertation can be summarized into the following sections:Firstly,the background and significance of developing the electromagnetic simulation methods for the composite structures are introduced,and the existing methods for solving this problem are presented.Secondly,electric field surface integral equation is deduced strictly based on the extinction theorem,then the integral equation is converted to discrete form according to the method of moments for the numerical calculation.Thirdly,a new way of domain decomposition is introduced and the theory of the aggregate basis function method is expatiated based on the new dividing method.Considering the periodicity of the periodic structures,the impedance matrix blocks of the periodic structures is calculated.The approximate solution of each domain in the periodic structures can be obtained by taking a small area to account.After the coupling between different domains of the periodic structures is analyzed,the aggregate basis functions of each domain can be achieved.The feasibility and validity of the proposed method to analyze the unconnected and connected periodic structures is demonstrated by two examples.Fourthly,the process of analyzing the combined structures by using the fast mutual coupling iterative algorithm is introduced.Based on the iterative algorithm,the approximate solution of each domain in the composite structures combined by periodic structures and other objects can be obtained,while the periodicity of the periodic structures is reused.After analyzing the coupling in the composite structures,the aggregate basis functions of each domain can be achieved.The feasibility,accuracy,and efficiency of the proposed method to analyze the unconnected and connected periodic structures with other objects is demonstrated fully by three examples.Finally,conclusions and future work are given.