Analysis of radio frequency interference in digital subscriber line systems

A numerical method for the analysis of a non-uniform multi-conductor transmission-line structure consisting of a bundle of twisted-wire pairs (TWPs) excited by a plane-wave electromagnetic field is presented. The intended use of such numerical method is to evaluate the susceptibility of TWP bundles to radio frequency interference (RFI) in digital subscriber line (DSL) communication systems. In the past, crosstalk noise in TWP bundles has been successfully characterized by modeling TWPs as a cascade of short uniform transmission-line sections rotated continuously. The presented model is an extension of this approach capable of including the effects of RFI. Computed and measured results for a variety of TWP configurations of interest to DSL systems are presented. Furthermore, the presented numerical method is used to analyze the role that twisting non-uniformities play in the susceptibility analysis of TWPs.