Extended Transmission Line Theory and Its Application to the Broadband Modeling of Ferrite-Based RF Transformers

In this article, an extended transmission line theory is derived and utilized to generate simple broadband models for ferrite transmission line transformers in the kilo- and megahertz range. Using the extended description of a transmission line leads to a compact element that can easily be inserted into the circuit of a device. The resulting models are verified through measurements of various transformers and produce qualitatively and quantitatively accurate predictions. Lastly, simulation analysis using CST Studio Suite confirms the internal physical behavior of the extended transmission line model, specifically its distinction between symmetrical and unsymmetrical currents.