Ag thick film microstripline as nondestructive dielectric and moisture sensor for soybean

By Vaishali Mane,Vijaya Puri


A cost effective miniaturized Ag thick film microstripline 1in x 1in was used as a nondestructive dielectric and moisture sensor for soybean. The in-touch overlay method provides ease of loading and unloading. The perturbation obtained in the transmittance and reflectance of thick film microstripline due to the Soybean overlay has been used to obtain the permittivity. The changes in the moisture content in the seed produces frequency dependent changes in the characteristics of microstripline. As the moisture content increases the dielectric constant and dielectric loss increases.  Microwave conductivity decreases with moisture content. A simple relationship between dielectric properties and bulk density is indentified, and a new density-independent function for moisture content prediction is proposed. Explicit calibration equations for moisture prediction at different frequencies and moisture contents are provided.


Key Words : Moisture sensor; Microstripline; Permittivity; conductivity; soybean; microwave.


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