Permittivity Extraction of Moist Soil for GPR Applications

In this work, the permittivity of sand and soil is studied as it varies versus their humidity content. It is well known that the permittivity of sand and soil increases with elevated humidity, since the water's dielectric constant is much higher. The aim of this work is to quantify this permittivity variation. The Transmission/Reflection method is used as the material characterization technique, where two rectangular coaxial transmission lines with different lengths are employed as the test fixture. The S-parameters of the fixture, with and without the material under test (MUT), are measured, and from these S-parameters a conversion algorithm is used to extract the permittivity of the MUT. The procedure for determining the humidity of sand and soil, for permittivity extraction, as well as the obtained results are reported in this paper.