Research And Application Of Electromagnetic Scattering Calculation Methods For Planar Thin Dielectric Structures

Thin dielectric structures such as frequency selective surfaces and metasurface materials are widely used in electromagnetic engineering.Therefore,the research on efficient,accurate,and resource efficient computational methods for such structures has important value and significance.Volume integral equation methods are often used to calculate electromagnetic scattering from dielectric structures,and tetrahedral meshes are used for subdivision.However,when the dielectric is very thin,problems such as difficulty in modeling,large amounts of unknowns,and long calculation time may arise,which makes the commonly used methods very inefficient in calculation.Compared to the commonly used SWG basis function,the application of simplified prism vector(SPV)basis functions has the advantages of easier grid construction,fewer unknowns,and less computational time when analyzing thin dielectric structures.Therefore,in this thesis,the SPV basis functions are selected to analyze thin dielectric structures.In this thesis,SPV basis functions are applied together with fast algorithms to improve the computational efficiency of thin dielectric structures.Firstly,this thesis applies the H-matrix theory to the electromagnetic scattering calculation of thin dielectric structures.The H-matrix theory is introduced,and the implementation principle and process of the adaptive cross approximation algorithm are described in detail.Next,the basic principle of the multilevel fast multipole algorithm is introduced.Combining the H-matrix theory with MLFMA,the calculation of the near groups of MLFMA are accelerated,and verified by numerical examples.Next,for thin dielectric periodic structures,the SPV basis functions are combined with the periodic Green’s function.The principle of the periodic Green’s function method is introduced,and numerical examples are given to prove the correctness and efficiency of the method.Subsequently,a hybrid method is proposed for certain quasi-periodic structures to reduce memory consumption.Finally,for the wideband problem of thin dielectric structures,the best uniform approximation method is introduced into the calculation to achieve efficient calculation of wideband electromagnetic scattering of thin dielectric structures.The principle of the BUA method is introduced in detail,and the solution process using the BUA method is briefly described.The numerical example shows that the calculation time is greatly reduced by adding a small amount of memory.