Characteristic of Electromagnetic Noise Based on the Theory of Multiconductor Communication Line

Electromagnetic noise has serious influence on the performance of electrical system. In addition, while multiconductor cable harnesses play an important role in transmitting electromagnetic energy or signal between devices of electrical system, they are also the major path to transmit electromagnetic noise. Crosstalk, as typical electromagnetic noise within multi-conductor cable harnesses, is an important factor which affects the efficiency of transmission. In this paper, the n+1 transmission lines (n=2, n>2) are taken as the object of research. Based on the theory of Multi-conductor Transmission Line (MTL), the transmission of electromagnetic noise in transmission line is studied, including noise of generating line (called G-line) and line receiving interference (called R-line), the latter called crosstalk. Transfer functions of electromagnetic noise of G-line and R-line are simulated using FEKO (FEldberechnung bei Korpern mit beliebiger Oberflache). Two transfer functions are obtained to investigate the severity of noise of G-line and R-line. The characteristics of the parameters are also studied. Simulation results indicate that transfer functions have tight relationship with the electrical length. When the electrical length is small, voltage loss of interference line along the transmission line is relatively small, so is the far-end crosstalk; however, when the electrical length is large, voltage loss and the far-end crosstalk is larger, and resonances at high frequency. Keywords: Electromagnetic noise; FEKO; electrical length;