Design and modeling of transmission line transformers

Equivalent circuitry for straight transmission line transformers (TLT) is presented. The circuits deploy transmission line theory to describe wave propagation of both the signal modes and the parasitic (ferrite) mode. The validity of this approach is demonstrated for two different TLTs. Both devices have an upper frequency limit of 5.5 GHz. Through the use of a single ferrite tube a lower frequency limit down to 1 MHz is achieved.