Characterization of soil moisture using a microstrip resonator

The development of a successful remote sensing instrument for soil moisture relies on the accurate knowledge of the soil dielectric constant relative to its moisture content. Two existing methods for measurement of dielectric constant of soil at low and high frequencies are, respectively, the time domain reflectometry (TDR) and the reflection coefficient measurement using an open ended coaxial probe. The accuracy of the measurements provided by both methods is limited. A microstrip resonator dielectric probe (MRDP) is proposed for the dielectric constant measurement of soil medium. In this technique the microstrip resonator is placed in contact with soil medium and by measuring the shift in the resonant frequency and change in the quality factor of the resonator, the real and imaginary parts of the dielectric constant are calculated. A prototype microstrip resonator at L-band is designed and measurements of soil with different moisture content are presented