Research On Numerical Algorithms And Development Of Simulation Software For Effective Dielectric Parameters Of Microwave Transmission Lines

Microstrip lines are widely used in various microwave integrated circuits and high-speed digital circuits,and their characteristic impedance and effective permittivity are important parameters that affect their signal transmission performance.As the operating frequency of the circuit increases,the microstrip line becomes smaller,the dielectric loss tangent increases,and dispersion characteristics of microstrip line are also more significant.Accurately extracting the parameters of the microstrip line at different frequencies has become increasingly important for circuit design.In this thesis,the engineering practical problems faced by single-layer Microstrip and multi-layer Microstrip under the wide band of 56 GHz central frequency are analyzed.The characteristic impedance and effective permittivity under various parameters such as different transmission line thickness,shape,dielectric thickness,loss,dispersion,etc.are simulated and analyzed,providing reference for practical requirements.In addition,based on the full wave analysis method-finite element method,the independent software for calculating the characteristic impedance and effective permittivity of Microstrip is developed.the parameter extraction algorithm of Microstrip and the finite element method of full wave analysis are introduced.The quasi-static analysis method,capacitance calculation method,scattering parameter extraction algorithm,effective permittivity extraction algorithm of Microstrip,as well as the principle and solving steps of finite element method are introduced in detail.The frequency characteristics of four types of parameters,including transmission characteristics,characteristic impedance,effective permittivity and loss tangent of Microstrip with different shapes under the 56 GHz broadband frequency of the center studied.The effective permittivity by using the dielectric parameter extraction algorithm is calculated.The impact on the transmission performance of Microstrip caused by the size parameters of the microstrip line produced in the project changing within 20% is analyzed.And The microstrip transmission performance under extremely poor parameters is analyzed.The frequency characteristics of four types of parameters in the case of multi conductor transmission lines are studied,mainly considering parallel coupled Microstrip and differential Microstrip,and the size parameter changes of 20%Microstrip and the analysis in the case of size difference are also analyze.These simulation data have guiding value for the project’s 56 GHz transmission line requirements and circuit board production.Modules based on the finite element method of full wave analysis are independently developed,including the grid reading module,matrix parameter calculation module,scattering parameter calculation module,and effective permittivity calculation module.Using the Qt tool,an application software integrating various analytical formula calculation and full wave numerical calculation for Microstrip parameter extraction is developed to meet various calculation requirements for Microstrip parameter extraction.