Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/27/2015
Publication Date: 8/14/2015
Citation: Lewis, M.A., Trabelsi, S., Nelson, S. 2015. Measurement software to facilitate free-space permittvity measurements on agricultural products. Applied Engineering in Agriculture. 31(4):545-552.
Interpretive Summary: As more technological advancements occur, many procedures that were once done manually are now automated by computers, greatly increasing efficiencies. Ten years ago, there was no software available to facilitate permittivity measurements on agricultural products using the free-space, transmission method. Measurements in the laboratory were done by hand, and certain experiments were not feasible because of the man-hours they required. Therefore, there was a need for software to automate these permittivity measurements. To address this need, user-driven software was developed within USDA ARS to automate measurements of the permittivity, or dielectric properties, of agricultural products. The software, which is executed on a personal computer, establishes remote control of a vector network analyzer and guides the user through the entire measurement process. Operations that required the pressing of several buttons to execute can now be done with one mouse click. The measurement software has facilitated research for which continuous measurements were taken at specified time intervals for periods of 24 hours or more. With this software, users are able to take discrete or continuous permittivity measurements on static samples and continuous measurements on dynamic, or flowing granular samples, accelerating progress on research that benefits farmers, product handlers, marketrers, and finally the consumers of agricultural products.
Technical Abstract: The creation of a user-driven software application to automate laboratory, free-space measurements of permittivity for cereal grain, oilseed, biomass, nuts and other agricultural products is discussed. A decade ago, there was no software available to aid in permittivity measurements using the free-space, transmission method. With the increase in need of laboratory permittivity measurements to aid the development of indirect methods for determining physical properties in agricultural products, there arose a need for such software. Therefore, software was developed within USDA ARS to facilitate free-space permittivity measurements on agricultural products at microwave frequencies, using the transmission method. The software establishes remote control of a vector network analyzer and guides the user through all steps needed to take accurate measurements at a single frequency or over a broad frequency range. The software also arranges and stores the data within the PC at a specified location. Solutions for attenuation restriction, phase ambiguity and time-domain gating are also provided. With the software, users are able to take discrete or continuous permittivity measurements on static samples and continuous measurements on dynamic, or flowing granular samples.