Analysis of dielectric properties of layered plastics at W-band frequencies

In this paper, we demonstrate an active 3D millimeter wave (mmW) imaging system used for characterization of dielectric multilayer materials. Reflectometry is used to obtain the evolution of the refractive indices of unknown materials over a frequency range between 75 GHz and 110 GHz, denoted as W-band. Depending on the measured strength of dispersion, precise localization of small defects such as voids or delamination in multilayer structures can be realized by mmW imaging using the same system.