| In recent years, microwave theory and techniques has been developed rapidly, the direction of its application not only reflected in the communications, electronic warfare and other information field, but also in the field of Chemistry and Chemical Engineering on the development of new materials and research. Accurate measurement of complex permittivity of dielectric materials will provide a strong scientific basis for development of new materials. East China University of Science and Technology has been committed to physical and chemical characteristics of pulverized fuel ash in recent years, in order to extract aluminum elements from the waste pulverized fuel ash. So, accurate measurement of complex permittivity of fly ash plays a vital role for analysis of fly ash physical and chemical properties at different temperature.In this thesis, we measure the dielectric constant and dielectric loss of fly ash by using the more mature method-----microwave cavity method. Based on this method, design some components used in the system set up test systems. This paper studies measuring method of resonant frequency and quality factor of the cavity when the microwave signal source can only provide a single frequency. Establish the equivalent model of the resonator, derive Theoretical formula of resonator quality factor, and designed a five-port network. In addition, establish a error model in order to measure more accurate result. Finally, automatic measurement software is designed to not only improve the measurement of efficiency, but also to facilitate the operator.The Features and innovations:(1) Find a new way to calculate the resonant cavity quality factor, which is different from the traditional method (3dB bandwidth)(2) Find a theoretical formula to determine the coupling of resonant cavity and the outside circuit(3) The system can measure the temperature and the dielectric parameters in the same time... |
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