Abstract: A new microwave measurement method for moisture content of grain is proposed. According to this method, a measurement system is designed for grain moisture content continuous measurement. In this system, moisture content can be measured by a specially designed microwave resonator which has a center hole. When grain passes through the center hole, its density and moisture will cause resonant frequency excursion (RFE) and microwave attenuation (MA) of the resonator. Under the same moisture, density is only related to MA. If RFE and MA are detected, we can calculate moisture content of grain, the change of density would not affect the calculating result of moisture content. In order to get high accuracy, a center-certain fuzzy clustering algorithm is proposed. According to the response characteristic of microwave resonator and the fuzzy clustering algorithm, we designed a high accuracy microwave measurement system which can measure grain moisture content in real-time. Experimental results show that the measurement system has high accuracy. Its accuracy is varied from 92 per-cent to 96 percent in different months.

Key words: Fuzzy clustering algorithm, Microwave measurement, Moisture