Taper Transmission Line Based Measurement—A Thru-Only De-Embedding Approach

Abstract

This article proposes a novel validated de-embedding approach to S-parameter measurement. This de-embedding approach benefits from the fully symmetric nature of the designed tapered transmission line test fixture and requires only a Through (THRU) standard. A key point of this approach is solving for a new coefficient <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$R_{x}$ </tex-math></inline-formula> , which is defined to take into account the inherent physical properties of the transmission network. Compared with previous thru-only de-embedding methods, the present approach is applicable to a significantly wider range of frequencies and offers more flexibility in the design of the test fixture. In addition, this approach simplifies multiport configurations compared with traditional complicated calibration methods such as Through, Reflect, Line (TRL). For validation purposes, symmetric two- and four-port tapered THRUs were designed and measured. This novel de-embedding approach is verified by comparison measurements with the classic TRL method or the HFSS simulation and shows a very good agreement.