Research On The Nondestructive Testing Technology Of Multilayer Microwave Dielectric Materials

Microwave materials have been widely used in a variety of applications ranging from communication devices to military satellite services,and the study of materials properties at microwave frequencies have always been among the most active areas in materials science,and electrical and electronic engineering.In recent years,with the development of high speed and high frequency electronic circuit system,it is necessary to have a comprehensive understanding of the complex permittivity of multilayer dielectric materials,especially for the nondestructive testing of materials.Based on this background,the research on the nondestructive testing technology of multilayer microwave dielectric materials is becoming more and more important.First of all,a variety of testing technology of complex permittivity of materials were introduced,and the advantages and disadvantages of the existing testing methods were compared,we choose the open-ended coaxial resonator to measure the multilayer dielectric materials.Then the corresponding measurement algorithm was studied,on the one hand,the coaxial open resonant cavity open the electromagnetic field distribution was analyzed,combining material resonant measurement method,the lumped equivalent circuit model of single layer material was established and improved,and extended to multilayer material measurement,complex permittivity solving formula of multilayer microwave dielectric material was obtained.On the other hand,from the point of view of statistical learning and the perturbation theory of materials,the technique of extracting the complex permittivity of multilayer material based on support vector machine?SVM?is presented.Secondly,measurement system hardware is designed,including the physical structure of cavity and the coupling device,and open-ended coaxial resonator model was established and simulated by HFSS electromagnetic simulation software,the optimized cavity and related equipment are produced.Finally,the measurement system is integrated,the measurement specifications are established,and the related debugging and algorithm calibration are completed.The single-layer and multi-layer standard dielectric material samples are tested by new system,measurement results were compared with the reference value,the measurement error are analyzed.The test system target of this paper is as follows: Temperature: 25? Frequency: 2-6GHz Measure range:?_r^?:1⁷;tan?:1×10^-35×10^-2Test error:|??_r^???_r^?|?5.0%|?tan?|?10%×tan??8×10^-4...