Submitted to: American Society of Agricultural Engineers
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/8/2003
Publication Date: 11/10/2003
Citation: TRABELSI, S., NELSON, S.O. NONDESTRUCTIVE MULTIPARAMETER MICROWAVE SENSOR. AMERICAN SOCIETY OF AGRICULTURAL ENGINEERS, ST. JOSEPH, MI. ASAE PAPER NO. 036129. 2003. Interpretive Summary: Sensors play an important role in modern agriculture. They are used in the field and at different stages during the processing of agricultural products. With highly automated industries, requirements of precision farming, and the need for real-time decision-making, there is a growing need for on-line sensors. Microwave sensors provide a suitable solution to meet some of these challenges. They can be used for example for moisture sensing in grain and seed. However, the use of microwave sensors for measuring the bulk density or packing density of grain and seed as well as moisture content is described in this paper. The concept of a multiparameter microwave sensor operating at a single frequency is very attractive economically and technically. Economically, a multiparameter sensor can replace multiple sensors based on different technologies and provide the same amount of information; thus, allowing considerable cost reduction. The availability of low-cost microwave components developed for wireless telecommunications offers more incentives for the commercialization of such a sensor for agricultural use. In this paper three methods of calibration are investigated for bulk density and moisture content sensing in wheat, corn and soybeans from measurements performed at a single microwave frequency of 10 GHz. The availability of such sensors developed from findings of this research would provide tools for better management of moisture content and quality maintenance and safety of agricultural products for American consumers and for export products as well.
Technical Abstract: The principles of a nondestructive multiparameter microwave sensor operating at a single frequency are presented. Three methods of calibration are investigated for simultaneous, independent determination of bulk density and moisture content in moist granular materials. The first calibration method is based on measured attenuation and phase shift through a layer of material in free space. The second and the third calibration methods are pemittivity-based and thus can be used regardless of the measurement technique. Performance of these calibration methods is tested for wheat, corn and soybeans at 10.0 GHz at room temperature.