Grain Moisture Content Measurement System Based on Time-Domain Transmission Technology

To measure the grain moisture content with time-domain transmission technology (TDT), electromagnetic wave propagation characteristics was studied to find the relationship of electromagnetic wave propagation and the dielectric parameters of grain. Basic structure of measurement sensor was designed to be coaxial transmission line based on TDT theories. The main parameters of the sensor were calculated. The measurement circuit was designed based on processing theories of high frequency electromagnetic signals. Grain samples with different moisture contents were measured by both TDT system and the standard drying method. The results show that TDT system with Quadratic curve measurement model is of desired measurement accuracy.