A microwave system for real-time, non-destructive moisture content measurement in agricultural bales

The estimation of moisture content (MC) in agricultural bales is crucial for ensuring product quality and preservation. However, current techniques, such as the drying method and hygrometers, are slow, destructive, or limited in sample representativeness. This work presents the Bale Attenuation Microwave Evaluation System (BAILS), an instrument for measuring microwave attenuation due to MC. BAILS allows a fast and non-destructive measurement directly in the field. The system operates at f = 2.44 GHz and analyzes the attenuated signal using a discrete Fourier transform-based algorithm. Experimental characterization of the prototype demonstrates its ability to detect MC variations in real samples and water solutions with different conductivities, showing a linear correlation between MC and attenuation. Tests on straw bales revealed high repeatability and a linear relationship between gravimetric moisture and measured attenuation, validating the proposed approach. BAILS enables fast, non-destructive, and full-bale moisture content monitoring directly in the field. Its robustness and repeatability, combined with its potential for integration with harvesting machinery, make it a promising tool for industrial-scale agriculture. It supports real-time quality control and efficient crop management.