Research On The Three-dimensional Distribution Of Complex Permittivity Of Microwave Materials

With the development of the microwave dielectric material performance test technology with each passing day, the test area including the non-destruction testing technology of the dielectric properties of the heterogeneous microwave materials, becomes more and more extensive. This paper, on the basis of this research background, makes a research on the 3D distribution measurement method of the microwave materials’complex permittivity. Analyzing various test methods and combining the project requirements, this paper finally chooses the open-ended coaxial resonator and has infered the corresponding test algorithm. In order to verify the reliability of the test system, the high Q cavity double-layer materials test algorithm which is of high precision is utilized.First of all, as the key component of the test system, the open-ended coaxial cavity and high-Q cavity are both designed. On the basis of analyzing some principles of cavity design, the key physical size and structure of cavity are obtained. The physical model of the cavity is simulated and optimized by the HFSS simulation software, then the final size of the open-ended coaxial cavity is determined.Second, the algorithms are deduced, which include the open-ended coaxial cavity’s single layer homogeneous materials and multilayer materials algorithms and the high-Q cavity’s double layer material algorithms. Before and after the open coaxial resonator loaded single homogeneous sample, the relationships between the changes of fringe capacitance, resonance parameters and the complex permittivity of the material are used to deduce the calculation equations for single homogeneous material complex permittivity.On this basis, the full-wave analysis method and the effective dielectric constant method based on perturbation theory are used to solve the complex permittivity of multilayer materials, and the corresponding formula have been deduced. In addition, the double layers materials’complex permittivity algorithms in high-Q cavity is obtained using the accurate field solution.Finally, two test systems are assembled and the respective algorithm is calibrated. After testing the self-produced single layer, double layers, triple layers samples using the corresponding test system, the test data has been calculated using the corresponding algorithm and the computation data is obtained finally. The comparison of calculation results and the error analysis have demonstrated that when testing the single homogeneous material’s complex permittivity, the open-ended coaxial resonator test system can satisfy the subject index as follows:Test temperature:25℃Test frequency:1-5GHzTest range:relative dielectric constant εT：1～5; loss tangent tanδ:1×10-6～5×10-3Test error；|△εr/εr|≤40% |△tanδ|<20%×tanδ+5×10-4...