Grain Moisture Detection by Using A-Scan Radar Measurement

Abstract

The amount of moisture in stored grain is an important factor which affects food safety and grain quality. A sensible and accurate detection of the moisture content in stored grain is of great significance. In order to detect the grain moisture content non-destructively, the ability of the electromagnetic (EM) wave propagating through the grain can be exploited. While the conventional methods such as capacitive, gravimetric methods are suitable for measuring of moisture of small samples, the EM-based method is more suitable to measure grain moisture of larger samples. In this paper, the wheat moisture ratio is determined by means of A-Scan radar measurement. The radar backscattering signal belongs to air and wheat filled bin are obtained using vector network analyser(VNA) between 1 to 6 GHz for a total of 75 discrete points. The range gating process covering the same interval is performed to both (air and grain measurements) range profiles obtained by taking inverse Fourier transform (IFT) of the A-scan data. Then, the dielectric constant of the wheat is determined using phase information of A-scan data and the grain moisture content is calculated using the dielectric constants of grain, dried grain and water. The wheat moisture ratio is found with 0.6% error compared to actual ratio.