Near-Field Measurements of Dielectric Properties of Granular Materials with Microstrip Antennas for Microwave-Sensing Applications

Feasibility of measurement of the dielectric properties for bulk density and moisture-content determination in cereal grain and oilseed with inexpensive microstrip antennas in the near field is discussed. Results obtained for wheat and soybeans with a pair of single-patch microstrip antennas operating at 5.8GHz and 24C are compared to those taken in the far field with a pair of focused-beam horn=lens antennas. The standard errors of calibration calculated for bulk density and moisture-content prediction from measurement of the dielectric properties in the near field are slightly higher than those corresponding to far-field measurements but remain within an acceptable error range.

References
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