Coupling Analysis Of Electromagnetic And Thermal Fields In Waveguide Devices

With the development of science and technology and the demand of practical engineering,microwave devices are gradually miniaturized and integrated,and the size has reached the nanometer level.The smaller the device is,the higher its sensitivity to temperature is.Therefore,the influence of electromagnetic thermal effect on the performance of such microwave devices is more significant.With the increasing complexity of microwave circuit,the efficiency and accuracy of traditional computational electromagnetics numerical algorithm can not meet the actual needs.Therefore,it is necessary to study a high-efficiency and high-precision analysis method.This paper presents a method based on finite element method(FEM),which combines domain decomposition method(DDM),multi front algorithm(MA)and adaptive cross approximation(ACA),to realize a precise and efficient analysis of complex models.This paper will introduce the following aspects:Firstly,the basic process of FEM to solve electromagnetic field problems is introduced,including the process of deriving the electric field control equation through Maxwell equation system,converting the electric field control equation into the linear equations of finite element by the basic function selection and variational principle,as well as the common boundary conditions.At the same time,the theoretical basis of electromagnetic thermal effect is also introduced.At the same time,the theoretical basis of electromagnetic thermal effect is also introduced.Secondly,a domain decomposition method of compressed finite element is introduced to solve the electric field.The process is to divide the model into a finite number of non overlapping subdomains in DDM,establish the finite element system matrix for each subdomain by FEM,establish the DDM system matrix by introducing the transmission conditions and Lagrange multipliers of adjacent subdomains,and compress the related matrix by ACA.Through solving the FEM system matrix of each subdomain by Ma,the subdomain field distribution is obtained,and finally the whole domain electromagnetic field distribution is obtained.At the same time,the solution efficiency is improved by controlling the LU decomposition accuracy.Finally,the transient and steady-state heat field distribution is analyzed.The process includes the establishment of thermal DDM system matrix by dividing the model,taking dielectric loss of medium as the heat source,introducing the Lagrangian multiplier of thermal science,and solving the distribution of thermal field in sub domain through Ma,and then the distribution of the whole region stable heat field can be obtained.The dynamic change of thermal field in the sub domain is solved by the transformation of time differential equation and difference equation and frequency domain transformation,which is used to analyze the transient temperature change of the model.