Increasing numbers of commercially available sensors claim to use the dielectric
response of grains and other agricultural materials to sense moisture and additional
properties. A review of past and current research in this area gives a basis for
investigating the efficacy and potential of one such instrument. A variety of materials,
including corn, soybeans, wheat, ground feed, and soils were examined. Potential factors
for varietal classification within and material type classification between samples was
determined to be impractical due to the strong confounding effect of moisture
Sensor electrode topology was briefly touched on, raising interesting questions about
effects of geometry in dielectric sensors. The effect of material presentation was also
evaluated for both static and flowing samples. Using continuously flowing samples,
several varieties of corn were tested to evaluate existing density independent moisture
functions and density functions. The results verified the effectiveness of many functions previously only studied in the microwave range for radio frequency instruments. In
addition, a new density prediction function was discovered to have significantly better
performance at radio frequencies.
University of Minnesota M.S. thesis. August 2010. Major: Biosystems and Agricultural Engineering. Advisor: Dr. Jonathan Chaplin. 1 computer file (PDF); ix, 77 pages.
Braun, Joshua D..
On impedance based RF dielectric sensors and applications in agricultural materials..
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