The effect of sample wall gap on dielectric measurement of circular-coaxial cell

We analyze the error caused by having a thin layer of dielectric material surrounding a cylindrical rock sample in a coaxial-circular measurement cell. We develop a full-wave model that can predict the fields inside the cell and the reflection coefficient from the coaxial-circular junction. Galerkin´s approach has been used to determine the electromagnetic fields in different parts of the cell by utilizing the boundary value problem. The reflection coefficient resulted from the analytical models are compared with COMSOL simulation for a known lossless dielectric thin layer.