Industrial scale electromagnetic grain bin monitoring

•Presentation of first industrial EM imaging system for grain storage bins using wheat.•Detection and 3D imaging of realistic grain spoilage spots.•Presentation of antennas which withstand the forces generated during bin loading/unloading. We present an Electromagnetic Imaging (EMI) system capable of detecting spoiled grain regions inside a large-scale grain storage bin. Stored grain represents significant economic and nutritional value to humankind, but despite this value, storage losses are common (estimated to vary from 2% to 30%). While there are many mechanisms that cause storage losses, virtually all of them involve higher temperature and/or moisture content of the stored grain. Increases in temperature and/or moisture both raise the complex permittivity of the grain. Our EMI system creates a 3D image of the complex permittivity through 24 antennas mounted on the side of the bin operating at a frequency of 93MHz, combined with a 3D Finite-Element inversion/imaging code. The antennas are designed to have both the desired electrical characteristics, as well as withstand the significant forces caused by the loading and unloading of the grain. Results with 55 tonnes of hard-red winter wheat in a ≈2500 bushel (80 tonne) bin show that our system is capable of detecting a small spoilage region (0.24% of total grain volume, 2/5 of a wavelength in size) inside dry bulk grain. The 3D EMI system is a viable method of detecting spoiled grain in industrial grain storage facilities.