Determination of Propagation Constant of Terahertz Dielectric Ridge Waveguide Using Noncontact Measurement Approach

This paper presents a detailed uncertainty analysis and tolerance analysis of the noncontact measurement approach proposed here for determining the propagation constant of the dielectric ridge waveguide (DRW), operating in 750–1000-GHz range. Two diagonal horns were used to guide the terahertz wave through the DRW without physical contact. The experimental procedure is described in detail in this paper. The expanded uncertainty estimates were determined for this noncontact measurement for the first time. The uncertainty of the propagation constant of DRW includes measurement uncertainty and truncation uncertainty. The truncation uncertainty is based on the error of a simplified calculated equation, used in determining the propagation constant of the DRW. A detailed uncertainty budget of the propagation constant is presented. The tolerance analysis shows that the measurement approach is insensitive to the misalignment of the experimental system.