An Open Transmission Line Method for the Dielectric Investigation of Bound Soil Water

A dielectric measuring technique, denoted open transmission line (OTL) method, has been developed. The OTL method is suitable for performing accurate permittivity measurements as a function of the sample moisture content, by allowing a free exchange of water with the environment. The characteristics of the OTL cell are presented, together with an electromagnetic model and a measurement approach to obtain the dielectric properties of porous materials as a function of the water content. A sensitivity analysis is conducted, comparing the performances of the OTL technique to those of other well known methods. The measurement results on a few dielectric materials are presented and discussed.