Time-Domain Measurements for Determination of Dielectric Properties of Agricultural Materials

A time-domain reflectometer (TDR) system was used to obtain data on the frequency dependence of the dielectric properties of a few agricultural materials. Values for the complex relative permittivity in the frequency range from about 30 MHz to 1 or 2 GHz were obtained from the reflection coefficient, which was calculated from the ratio of the Fourier transforms of the incident and reflected waveforms from the dielectric sample in a coaxial line. With the TDR system, broad dielectric dispersion and absorption regions, similar to those found by frequency-domain measurements, were determined with significant reductions in time and effort.