Analysis of the current distribution induced on a victim wire by a differential voltage source applied onto a twisted pair cable

This paper focuses on the coupling between a twisted pair cable (TPC), which is modeled as a perfect helix of two conductors, and a single wire. The simulation of the current on a victim wire induced by a TPC made of a single twist gives non-obvious patterns depending on the starting angle of the TPC. An analytical model based on a circuit representation is developed in order to understand these specific current distributions. A coarse simulation of the TPC is first carried out with a minimum number of tubes that exhibits the same behavior as a finely discretized model. Then, the circuit approach applied in this case shows the influence of the arrangement of inductance and capacitance mutual terms along the twisted pair on the distribution of the currents on the nearby wire. It eventually explains the specific role of the starting angle.