I have been working up a spice model of a transmission line

transformer that approximates it with 16 inductances and 17

capacitances. It was meant to model a transformer wound through two

flat cable cores, so that the winding pair runs straight down the

slots, with the ends as far as possible from each other. It includes

the 120 mutual inductance coupling factors that model the reduction of

coupling efficiency as turns get further apart and both the normal

transmission line capacitance per length and the capacitance between 1

turn and the next of the pair. The responses have not been tested

against actual measurements, but they look quite reasonable, as long

as the phase shift per inductance segment is a small part of a cycle.

I selected the inductance and capacitance values to fit test data on a

particular example, but you can change them.

I built it for LTspice, free download at:

http://www.linear.com/company/software.jsp
If you would like to have a copy of this component model and its

symbol file, email me.