Non-Standard Waveguide Calibration with the Use of LRT-Method

Abstract

The usage of non-standard waveguides, e.g. single or double ridge waveguides, can give us big technical advantages relative to conventional solutions. The bottleneck of using such waveguides is that estimation of the measurement uncertainty is a formidable task. The most popular VNA calibration method TOSM (SOLT) uses match standard, which cannot be characterized by standard approach. The usage of TRL-method is restricted because characteristic impedance and wave propagation constant cannot be directly calculated form the geometry of some non-standard waveguide types. The authors offer LRT-method as an alternative solution for VNA calibration. New method uses minimal calibration kit like the already known TRL-method: electrically long line as match, direct waveguides connection as through, short or open as reflect standard and iterative procedure to calculate 8- or 12- error terms models. Since standard-to-non-standard waveguide adapters are used with serial produced VNAs, authors suggest to estimate uncertainty in reference to results, which were estimated in standard coaxial or rectangular waveguide with TOSM calibration.