Numerical studies of the electromagnetic reciprocal influences of symmetric communication cable

Abstract

The reciprocal influences between chains of symmetric communication cables is considered based on mathematical simulations of electromagnetic processes. It is assumed that the electric- and magnetic-field force lines are situated in the plane perpendicular to the cable axis and, therefore, the mathematical models describing the electric-potential distribution and components of the vector magnetic potential of alternating currents in a complex form can be presented in a two-dimensional setting. Differential equations written in the Cartesian coordinate system and describing the electric and magnetic potential distributions are solved by the finite-element method. The electromagnetic processes are studied numerically for the UTP Cat 5e LAN cable used in the structured cable networks. Such an approach allows one to determine electric- and magnetic-field distributions and calculate the coefficients of capacitive and inductive coupling in the cross section of a symmetric cable for a preset position of twisted pairs. The main way to reduce the reciprocal influences in unshielded symmetric communication cables is appropriate selection of twist pitches. The twist pitch in each chain should be chosen such that the integral of the capacitive and inductive coupling coefficients over a length of the symmetry section between all the cable chains tends to zero.