Permittivity measurement of a thin slab centrally located in a rectangular waveguide

The possibilities of permittivity measurement of sheet materials using a thin slab centrally located in a rectangular waveguide are discussed. The results obtained by several authors are commented on, and some new methods for the solution of the characteristic equation of the fundamental mode and for the measurement of the propagation constant of the dielectric loaded guide in the case of high and low loss materials are proposed. The conditions of single mode propagation are presented in the form of curves. Measurement results on perspex are given in X-band with an estimation of the possible errors.