Research On New Method For Measuring Dielectric Constant Of Microwave Samples

Detecting and measuring dielectric characterization of material is a dispensible part in the fields of material. With the development of more and more new materials, new methods for measuring these are a must in order to know the characteristic accurately.Recent years an artificial material named left-handed materials is focused on by scientists from all fields,particularly from fields of materials,optics and electromagnetic,and research on these has been on the increase.Due to its special electromagnetic characteristic(whenεandμare both negative the relations among E,H and S are left-handed,a new case about electromagnetic wave propagation happens. So in the beginning of the article it describes the progress in measurement methods of complex permittivity of materials,and compared to different methods it brings shortcomings and scopes.Further more,we calculate the propagation characteristic in the left-handed materials with Maxwell equations and constitutive equations.In order to meet the need of projects,the article provides a new method for measuring dielectric constant based on free-space method,and it successfully solves the problems of edge diffraction and multi-reflection in traditional method.And after theorically analysising the whole processes of measuring dielectric constant an equation related to dielectric constant of material and magnitude and phase of S parameter occurs.According to the devices in labs and experimental condition, many researches including building the system,TRL calibration,measuring and stimulating by matlab are made. Experimental systems described in the article include antennas,mode transitions,vector network analyzer,ranging system,laser calibrator and absorbing material.And the vector network analyzer is Anritsu 37347d.All processes are made in microwave laboratory. The experimental results of teflon and epoxy resin in the microwave laboratory indicate:The measured results are coincident with widely accepted data, which verifies that the method proposed here is feasible.