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ARS Home » Research » Publications at this Location » Publication #115320
Title: MICROSTRIP ANTENNAS FOR DIELECTRIC PROPERTIES MEASUREMENTS AND MOISTURE CONTENT SENSING

Author
item RAMAHI, OMAR - COMPAQ COMPUTER CORP
item TRABELSI, SAMIR - UNIVERSITY OF GEORGIA
item Nelson, Stuart

Submitted to: Progress in Electromagnetics Research
Publication Type: Abstract Only
Publication Acceptance Date: 8/28/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Microwave dielectric methods can be used to determine physical properties of materials such as moisture content and bulk density nondestructively and in real time. The accuracy with which these entities are determined is mainly dependent on the accuracy of the complex permittivity measurements. The sensing elements, or antennas, are ideally placed in close proximity to othe material without disturbing the moving material. The constraint imposed by placing the measurement antennas close to the material puts the material in the near field of the antennas. In this study, effects of the near-field measurements on the accuracy of the complex permittivity prediction are analyzed. More specifically, we develop a measurement model where microstrip antennas are used for the transmitter and receiver, with the space between them filled with a moist granular material of dielectric constant between 2.1 and 5.0 and dielectric loss factor between 0.1 and 1.2. A numerical model is developed using the three-dimensional Finite-Difference Time-Domain (FDTD) method. A full description of the FDTD model will be presented highlighting the effectiveness and limitations of the FDTD method in the study of complex media. Simulation results will be presented and compared to physical measurements for three cereal grains and soybeans.