Millimeter-wave absorption measurement of silicon carbide powder by free-space method (Part 1) - Investigation of measuring method for powder sample

Millimeter-wave absorbability of β-silicon carbide powder was measured by free-space time-domain method at the V- and W-bands millimeter-wave regions. A sample holder consisted by two Teflon disks and an acryl sleeve was used to fix the powder sample. The affection of sample holder insertion on the free-space measurement was estimated within 0.3 dB by S-parameter measurements. Noises in S parameter profiles could be excluded by applying a time-gate at the peak around 0 ns. Dielectric constants of β-silicon carbide at microwave region were measured by the coaxial probe method as a reference. Dielectric constants of β-silicon carbide showed frequency distribution at microwave region, but the change of loss tangent (tanδ) at millimeter-wave region was small. The loss tangent curve was almost flat and the value was between 0.09 and 0.13 at millimeter-wave region.