Using cereal grain permittivity for sensing moisture content

A brief history of cereal grain moisture measurement by sensing the electri cal properties of grain is presented. The basic principles are also describ ed for using radio-frequency (RF) and microwave dielectric properties, or p ermittivity, of grain for sensing moisture through their correlation with m oisture content, The development of density-independent functions of the pe rmittivity is explained. The findings of recent research are summarized, wh ich indicate that reliable density-independent moisture content determinati ons can be realized by measurements on grain at RF and microwave frequencie s. Development of these techniques will provide useful instruments for on-l ine monitoring of moisture content in flowing grain to manage moisture in g rain, prevent spoilage in storage and transport, improve processing, and pr ovide information important for yield determinations in precision agricultu re applications.