W-band Dielectric Characterization of Automotive Paint

A rectangular waveguide sample-holder is proposed for characterization of dielectric constant of thin sheets, where the sample is mounted in the longitudinal direction. This is a desired configuration as it provides higher sensitivity in measurement of complex dielectric constant and ease of sample preparation for WR-10 waveguides. Unlike conventional rectangular waveguide techniques, this technique relies on the resonance behavior of the reflection coefficient from the sample to accurately estimate the dielectric constant of the sample under test. A rectangular waveguide sample holder was fabricated, and different samples were characterized. The estimated dielectric constant values were verified using a CPW resonator technique.