Click on “Download PDF” for the PDF version or on the title for the HTML version. If you are not an ASABE member or if your employer has not arranged for access to the full-text, Click here for options. MEASURING DIELECTRIC PROPERTIES OF HARD REDWINTER WHEAT FROM 1 TO 350 MHZ WITH A FLOW-THROUGH COAXIAL SAMPLE HOLDERPublished by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org Citation: Transactions of the ASAE. 41(1): 143-150. (doi: 10.13031/2013.17138) @1998Authors: K. C. Lawrence, S. O. Nelson, P. G. Bartley Jr. Keywords: Grain, Moisture content, Dielectric properties, Wheat, Coaxial sensor A system for measuring the dielectric properties of cereal grains from 1 to 350 MHz with a coaxial sample holder is presented. Several polar alcohols were used to calibrate and verify permittivity measurements obtained with a signal-flow graph model from the full two-port S-parameter measurements. At the lowest frequencies (1-25 MHz), where the phase measurements are less accurate, a lumped parameter model was used for the dielectric loss factor measurements. The system was calibrated with measurements on air and decanol and verified with measurements on octanol, hexanol, and pentanol. The standard error for the polar alcohols used for verification was 2.3% for the dielectric constant and 7.6% for the dielectric loss factor. Although measurements were taken on static samples, the sample holder is designed to accommodate flowing grain. Dielectric properties measurements at 25C were taken on four hard red winter wheat cultivars ranging in moisture content from about 9% to 21% with bulk densities varying from 0.66 to 0.83 g/cm3. Most of the data agreed with measurements reported in the literature. (Download PDF) (Export to EndNotes)
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