Determination of complex permittivity using a scalar quasi-optical measurement system in the E-band

We developed a low-cost quasi-optical measurementsystem to determine the complex permittivity in the E-band (from 60 to 90 GHz]. The evaluation is done in a non-destructive way and can be used for all kinds of single-layered and multi-layered dielectric materials. The method is based on measurements of the scalar transmission coefficient through planar samples for several angles of incidence and two different polarization states. A numerical optimization technique is used to derive the complex permittivity from the measured coefficients. The method utilizes a physical model of a dielectric slab of known thickness, which assumes that a plane wave is incident on the surface of the dielectric material. Measurement results are presented, which are in good agreement with data from a similar system using vector measurement.