Taper Transmission Line Measurement— A Thru-Only De-embedding Approach

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 Rx, which is defined to take into account the inherent physical properties of the transmission network. Compared to 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 multi-port configurations compared to traditional complicated calibration methods such as 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.