Sub-Terahertz Complex Permittivity Measurement Method Using Cavity Switches

New method of measurement of dielectric constant and loss tangent for small samples of lossy dielectrics, including plain semiconductors, using non-oversized resonators being parts of the recently developed cavity switches for sub-terahertz bands is proposed. Strong influence of the tangent loss value to the Q-factor of the resonator is calculated and observed in experiments. A simple monosemantic algorithm to retrieve explicit mathematical expressions for the complex permittivity from the experimental data is demonstrated. The advantage of the new method over the known ones is much lower (up to million times) volume of the sample needed to analyze.