Characterization of 60-GHz silica-based post-wall waveguide and low-loss substrate dielectric

This paper presents the measured propagation constant of a low-loss fused-silica-glass-based post-wall waveguide (PWW) designed for the 60-GHz band and proposes a simple estimation method of relative dielectric constant and loss tangent of the substrate dielectric from the propagation constant. The attenuation constant α of the PWW at 60 GHz is as low as 0.013 dB/mm. The relative dielectric constant and loss tangent are estimated by performing eigen-mode analysis using a commercial 3D electromagnetic software. The estimates are consistent with those from a conventional cavity resonator-based method. Unlike resonator-based methods, no additional samples are needed to provide estimates of dielectric properties at multiple frequencies.