THRU-REFLECT Method for Scattering Parameter Extraction from Back-to-Back Measurements of Waveguide Components

The design of new waveguide components is often verified by back-to-back measurements of two identically fabricated units without extracting the characteristics of a single device. This paper presents a simple method of extracting the scattering parameters of waveguide components from back-to-back measurements. The proposed method requires only three waveguide mating connections: one for reflection measurement with an offset SHORT and two for transmission measurement with a THRU configuration. A singular condition in the S-parameter extraction equations is derived, and the optimum length of an offset SHORT standard or a reflecting load is determined based on the singularity condition. The numerical simulation of a broadband coax-to-waveguide transition is employed to show the workings of the proposed method.