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ARS Home » Research » Publications at this Location » Publication #121029
Title: UNIVERSAL CALIBRATION FOR MICROWAVE MOISTURE SENSORS FOR GRANULAR MATERIALS

Author
item TRABELSI, SAMIR - UNIVERSITY OF GEORGIA
item Nelson, Stuart
item Kraszewski, Andrzej

Submitted to: Instrumentation and Measurement Technology Conference Record
Publication Type: Proceedings
Publication Acceptance Date: 3/1/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary: New reliable techniques are needed for rapid on-line sensing of moisture content in grain and seed when being harvested, transported, and processed for food and feed products. Microwave measurement techniques have been discovered that can provide reliable moisture content information on grain and seed materials while they are moving through chutes and conveyors, but suitable practical equipment utilizing the techniques have not yet become available for practical application at costs that are justified by agricultural equipment manufacturers. Calibration of such instruments for each individual kind of grain and seed has been necessary in the past for sufficiently reliable performance of moisture meters, and this constitutes an important expense in the development and maintenance of electronic grain moisture sensors. A new calibration for microwave moisture sensors has been developed that provides sufficiently accurate moisture measurement with a single calibration for wheat, oats, and soybeans. Since these commodities are much different in the shape and characteristics of their kernels and in their composition, the calibration method appears promising as a universal calibration for grain and seed. Thus, the microwave moisture sensing method, with a single calibration for all grain and seed of interest, offers an economic incentive for the further development of practical instruments for commercial application. The availability of economical, reliable moisture sensors for on-line use will provide important advantages in product quality maintenance and improvements in efficiency of modern agriculture.

Technical Abstract: A universal calibration method for microwave moisture sensors for granular materials is presented. The method is based on measurement of the dielectric properties and the use of a complex-plane representation of the normalized complex permittivity. Effectiveness of this method in moisture content prediction is tested for granular materials presenting significant structural and compositional differences. A single moisture calibration equation is given at 9.46 GHz and 24 degrees C for wheat, oats, and soybeans that has a standard error of less than 0.5% moisture content.