| Microstrip circuits,as an important RF circuit structure,find wide applications in wireless communication,radar systems,and microwave sensors.Accurate determination of the microstrip line’s dielectric parameters is crucial for circuit design and optimization.Traditional methods for dielectric parameter extraction rely on experimental measurements,which suffer from experimental errors,measurement complexity,and limited theoretical applicability.In contrast,more general and versatile dielectric parameter extraction algorithms are based on full-wave numerical methods.This study primarily focuses on a dielectric parameter extraction algorithm based on the FiniteDifference Time-Domain(FDTD)method.By extracting the scattering parameters of the microstrip line,we investigate the ABCD method for extracting the dielectric constant and the method for extracting the loss tangent.Finally,a specialized electromagnetic simulation software for dielectric parameter extraction is developed using software engineering techniques.The main contributions of thesis are as follows:Firstly,we introduce the theoretical foundations of the FDTD algorithm and dielectric parameter extraction,along with key techniques based on the FDTD algorithm and modular software engineering concepts.The microstrip line FDTD simulation is divided into spatial modeling,grid partitioning,CPML absorption boundary,and excitation source modules,with additional modules for handling lossy dielectric and script parsing,providing flexibility in controlling the simulation.We analyze examples of lossless dielectrics,lossy dielectrics,and lossy copper-clad microstrip lines,and verify the numerical extraction methods for scattering parameters.Secondly,based on the classical transmission line method for dielectric parameter extraction,we investigate the traditional S-parameter inversion analysis method and successfully apply it to the extraction of the microstrip line’s dielectric constant.Subsequently,we adopt the ABCD method based on the transmission line model for extracting the dielectric constant of the microstrip line.We also implement the extraction of the loss tangent based on the power loss principle.Finally,we analyze the accuracy of dielectric constant extraction using the ABCD method and the traditional S-parameter inversion analysis method under different input parameters,while discussing the influence of microstrip line thickness and material on the accuracy of loss tangent extraction.Finally,based on the software engineering MVC framework,we use the C/C++ Qt development tool to develop the professional electromagnetic simulation software interface for dielectric parameter extraction.We encapsulate the algorithm modules using an object-oriented programming approach and use Open GL technology to develop a twodimensional curve visualization module for computing data.We also integrate the simulation control script parameters into the simulation software through text editing.Finally,the development of simulation software for extracting numerical values of dielectric parameters has been successfully achieved. |
