The Dielectric Material Of Dielectric Parameters Of Open Waveguides Measurement Method

A microwave nondestructive detection and evaluation (NDE) technique used to measure complex permittivity of isotropic materials has been developed in this paper by employing a flanged open-ended rectangular waveguide probe over a frequency range of 8-12GHz.Based on a Fourier transform boundary matching technique and waveguide theory, two coupled integral equations for the aperture electric field which is coupled with a stationary form of the terminating aperture admittance of the waveguide are formulated, and then, the model describing the equation between the terminating admittance which can be measured and the aperture E-field which contains the information of permittivity is constructed based on the variation expression for the terminating aperture admittance. The unknown permittivity will be derived in the inverse problem using optimizing algorithm.Considering the influence of different factors such as frequency, complex permittivity and thickness of the materials, a series models have been stimulated in AnsoftHFSS, the stimulating results certificate the validity of the models. Furthermore, the results have also been compared with some experiments; good agreement with each other proved that the method of open-ended waveguide measurements has sufficient accuracy and it also able to be applied in nondestructive on-the-worksite testing.