The operation and modeling of transmission line transformers using a referral method

This article describes the modeling of transmission line transformers using methods which are analogous to the methods used to analyze both the ac fre quency and transient response of conventional transformers. Transformers in which the lines used to construct them are wound inductively, in order to suppress parasitic short circuit paths within the transformers, are analyze d. It is shown that by using this technique the resulting inductive isolati on of the secondary circuit from the primary substantially reduces pulse dr oop and pulse distortion. Despite the apparent complexity of these transfor mers, a method by which circuit models of these transformers can be deduced is given. From these models very simple equivalent circuits can be derived which can then be used to calculate accurately the performance characteris tics of the transformers and, in particular, predict the pulse distortion c haracteristics of these devices. Different winding configurations are also considered and it is shown that, by the use of mutually coupled winding of the transmission lines in the transformer, it is possible to minimize pulse droop. Finally it is shown that the modeling technique can be used, in mod ified form, to analyze the ac frequency response of this type of transforme r. (C) 1999 American Institute of Physics. [S0034-6748(99)00907-7].