The Reseach And Design Of The Microwave Resonant Cavity For Material Moisture Measurement

In order to ensure the quality and quality, objects and products must have certainmoisture content, so it is necessary to measure and monitor the moisture content of thematerial in the life, especially in industrial production. The microwave resonant cavitymethod of measuring material moisture which has the advantages of high accuracy, fastresponse, online measurement, has been widely studied in recent years.By the study of the distribution of the electromagnetic field of the resonant cavityperturbation principle and cylindrical cavity and comparing to other moisture measurement ofthe advantages and disadvantages of the cavity, this paper proposes a new type of materialmoisture measurement sensor-slot array split cylindrical cavity. This paper researches andsimulates the cavity and the use of the resonator for measuring moisture content by means ofsoftware simulation.First, the electromagnetic characteristics of the cavity for measuring moisture contentare analyzed, based on the theory of the resonator design of the size, the resonant frequencyand the coupling mode of the resonator, and through the research of the slit array principle,the size and spacing of the slot array is designed; The simulation using CST software on thesize of the various parts of the resonator is done; By the simulation comparison of the widthof the slits on the resonant cavity, the influence of the thickness of the protective plate, theslot array of the needle coupling and ring coupling mode, this paper obtains the optimalperformance of the resonator cavity dimensions. Resizing of the optimized resonator andloading experiments shows the feasibility of the design. Material object is produced inaccordance with the result of the simulation and is in accordance with the design requirementsthrough testing.Secondly, the resonator for measuring moisture content is researched. Material moistureand a relational expression of the dielectric constant on the dielectric constant of the mixturemodel is deduced, according to the relationship of the resonant frequency and the measuredmaterial permittivity which is deduced by researching the electromagnetic field distribution ofthe principles of the resonant cavity perturbation and resonant cavity. Through the simulationof different moisture content of the tested materials, the relationship of the resonant frequency and material dielectric constant is determined, finally, the equation of the material moistureand resonant frequency is determined, the cavity is successfully applied for material moisturemeasurement.This work has significant reference for the practical application of the resonant cavitymethod for measuring moisture content; the design of the cavity can be better used for themeasurement of material moisture, but the hardware components of the measurement systemand the practical application needs to be further studied.