Automated cable coupling analysis software for EMC prediction

Abstract

Electromagnetic (EM) coupling between cables containing shielded twisted pairs can cause system degradation, i.e., powerline noise induced onto cables used for communication. Software that uses mathematical models of differential- and common-mode coupling between shielded twisted pairs is described. The differential-mode coupling model is derived from Ampere's law and the Biot-Savart law. The common-mode coupling model is based on the percent imbalance in cable-shield current and inductance due to cable-shield distance from a ground plane. EM data tables and a set of routines using these models were generated using structured query language embedded in Fortran. A novel approach was taken to ensure correct results and reduce user error: the program accesses a large existing knowledge base of cable electrical and physical properties, requiring only cable designators and positions from a user to obtain an interference evaluation.<>