Simple Nondestructive Method for the Measurement of Complex Permittivity

A simple nondestructive method is presented for the measurement of the complex permittivity ¿r of materials. The reflection coefficient ¿ of a flanged open-ended rectangular waveguide placed, next to a flat large sample is computed by a variational method as a function of the dielectric constant. Computer-generated charts and an optimization computer program are elaborated. ¿r can then be easily determined from the measured amplitude and phase angle of the reflected wave in the waveguide. The method is best suited for materials having high dielectric constants and large losses.