A simple method for measuring the dielectric constant of solids

This paper presents a simple method for determining the dielectric constant of a solid material. The method consists of measuring the return loss due to a slab of such material inserted into a rectangular waveguide. The diele ctric slab presents a discontinuity inside the waveguide, and the electric field at each interface of the slab is described as a summation of weighted sinusoidal basis functions. The scattered magnetic field on either side of the slab is determined using the modal expansion approach. These weights a re solved by using the method of moments on the boundary conditions of cont inuity of the tangential magnetic field at the interfaces. The component of the electric field (scattered) for the dominant TE10 mode can then be dete rmined in terms of these weights, and from this result the reflection coeff icient can be theoretically evaluated, A comparison between the experimenta lly obtained reflection/transmission coefficient and the theoretical values provide a figure for the dielectric constant of the material.