A Large Scale Characterization of the Dielectric Properties of Heterogeneous Layered Rock Salt

Abstract

Although there are several methods described in the literature to accurately measure the complex permittivity of solid dielectrics at radio frequencies in a laboratory environment, none of these methods allow for a large-scale accurate characterization of natural ionic dielectrics. The work presented here reports results of the dielectric permittivity retrieved from in situ measurements in a Romanian salt mine. Measurements were performed in the 164-174-MHz bandwidth, over a propagation distance of 100 m. The characteristics of the layers of sedimentary salt are determined from measurements using a least mean square fitting algorithm, based on a detailed propagation model for a heterogeneous medium. The coupling of the instrumentation is also considered. The proposed approach demonstrates great promise for a large number of applications.