Journal of Microwave Power and Electromagnetic Energy (JMPEE)
TITLE	Resonant Cavity Perturbation – Some New Applications of an Old Measuring Technique [PDF]
AUTHORS	A. W. Kraszewski and S.O Nelson 1996 31 3 178-187
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Abstract Microwave resonators have been used as sensors for determining material properties of dielectric objects, including permittivity, density, moisture content, and mass, from measurements of frequency shift and change in cavity transmission characteristics when a small dielectric object is inserted into a microwave resonant cavity. Fundamental principles of the shape- and size-independent measurements are discussed and experimental results for moisture content and mass measurement of individual soybeans, peanuts and grain kernels, as well as for mass determinations on irregularly shaped objects of common plastic materials are presented. Measurements are fast, nondestructive, contactless, and have the potential for continuous operation. Key Words: Resonant cavity measurements, Microwave resonators, Permittivity, Density, Mass, Moisture content, Grain kernels, Dielectric properties, Plastics.