Low-loss millimeter-wave propagation in silicon-based suspended dielectric image guide

Transmission loss of E₁₁^x and E₁₂^x modes in suspended dielectric image guide is measured at about 100 GHz. Commercial high-resistivity silicon is used as a low-loss dielectric. Dielectric loss tangent of the silicon is measured separately at 100 GHz in a rectangular waveguide resonator test fixture as (1.5±0.5) × 10^-4. A copper metal image guide resonator fixture of 22.83 mm length is used to determine transmission loss of the image guide modes. Measured loss of E₁₁^x mode is within 14.6 dB/m to 22.1 dB/m. Measured loss of E₁₂^x mode is 3.24 dB/m to 3.72 dB/m. These loss values are much lower than loss of typical substrate-integrated waveguide, they compare well with loss of co-axial cable, and come close to the loss of air-filled rectangular metal waveguide.