A novel method for measuring the moisture distribution of grain in the silo based on microwave image technology

Grain moisture is a key indicator of security, however, it is lack of online technology for detecting moisture distribution. In this paper, the microwave image method using a rotatable reflector has been proposed to solve the problem. Firstly, a detection probe was designed. Then, we use FDTD (Finite-Difference Time-Domain) method to simulate the microwave propagation process in a grain silo. After that, a one — dimensional moisture distribution inverse model has been built to process reflection signal. At last, an image of moisture distribution is generated based on a linear combination of all one — dimensional data. After analyzing the result, the proposed method can precisely image grain moisture, especially in normal area and the center of the abnormal area, where the error is less than 0.5%. Furthermore, the profile and size of the abnormal area can be clearly identified. Above all, the proposed method can meet the demands of online moisture distribution of grain in a silo, and it has great application prospect.