Robust Estimation of the Dielectric Constant of Cylindrical Objects Using Wideband Radar Transmission Measurements

The article proposes a method of estimating the dielectric constant or propagation velocity of a cylindrical object. The method is simple but robust, completely noninvasive, and suitable forin situuse. The method employs a set of transmission measurements, which record travel times through the object with various path lengths. The shape of the arrival time curve is evaluated and the dielectric constant that best describes the curve shape is obtained as the estimate. The measurement configuration can be seen similar to that of common shot, common midpoint (CMP), or multioffset measurement in ground-penetrating radar (GPR) measurements. The proposed method was demonstrated using synthetic data and in laboratory experiments using a tree log and cemented sand samples with various water contents. The results indicated that the dielectric constant was reasonably estimated by the proposed technique, with an estimation error at least within 10% for the experiments discussed in this article.