Using Orbital Angular Momentum (OAM) Modes on Multi-Conductor Cables for Crosstalk Mitigation

In this paper the possibility to use orbital angular momentum (OAM) modes on a multi-conductor cable to mitigate crosstalk is presented for the first time. OAM modes are understood here as a general method to excite an electromagnetic system that shows cyclic symmetry. It is demonstrated that the OAM modes, known from antenna communication, are an extension of the known modes in two and three conductor systems. It will be shown analytically that the OAM modes are the eigenmodes of a cable showing cyclic symmetry and can therefore propagate on the cable theoretically free of crosstalk. The OAM modes are then compared to the pairwise differential modes in a simulation with regard to crosstalk. For this comparison a circularly arranged multi-conductor cable as well as a cable where the conductor pairs are closer together are evaluated. For the modeling of the per-unit-length parameters a two-dimensional (2-D) solver based on a boundary element method (BEM) is used.