Research And Design Of Measuring Device For Electromagnetic Parameters Of Microwave Materials

In recent years,with the rapid development of microwave technology,higher requirements have been imposed on the electromagnetic properties of materials.Permittivity and permeability are two significant electromagnetic parameters of microwave dielectric materials.Therefore,it is imperative to study the method of measuring electromagnetic parameters with high accuracy.This paper uses the network parameter method,and the resonant cavity method to measure the electromagnetic parameters of dielectric materials as research content,then designs and verifies the measurement devices manufactured by the above two measurement methods,including:(1)The basic theory of the electromagnetic parameter measurement.The physical meanings of two ordinary electromagnetic parameters,complex permittivity and complex permeability,were concluded through theoretical analysis and formula derivation.The transmission line theory and the elementary theory of the cylindrical cavity were established to pave the way for the design of subsequent measurement devices.(2)An electromagnetic parameter measuring device based on a stripline is designed.Proceeding from the mathematical model of the system,the functional relationship between the S parameter and the electromagnetic parameters of the material was theoretically deduced using the multiple reflection superposition method,and the size of the measuring device established by calculation combined with CST simulation.When checking the validity of the measurement system,the electromagnetic parameters of non-magnetic materials and magnetic materials were inversely calculated at 0.5 to 5 GHz using simulation methods.Secondly,physical processing was performed and we used a vector network analyzer to assess the electromagnetic parameters of several common materials.Finally,the reasons for theerrors were discussed.(3)Based on the cylindrical cavity mode theory,a parallel plate resonator measurement device which is capable of measuring the relative permittivity with high accuracy at a single frequency point is designed and fabricated.After determining the size range of the fixture and material,the inversion verification was performed from the aspects of simulation and experiment,and compared with the measurement results of the stripline method.The devices developed in this paper are verified from the direction of theoretical analysis,numerical simulation and experimental measurement.The measurement errors are lower than 5%,which proves their feasibility in practical engineering applications.It has evident reference value for the research of electromagnetic parameter measurement technology.