Applications of Multiconductor Transmission Line Theory to the Prediction of Cable Coupling Volume IV. Prediction of Crosstalk in Ribbon Cables.

Abstract

Abstract : The prediction of crosstalk in ribbon cables is investigated. Experimental results are obtained for a 20 wire ribbon cable and compared to the predictions of the multiconductor transmission line (MTL) model. Based on the experimental configuration tested, it would appear that accurate predictions of crosstalk can be achieved in controlled characteristic cables such as these. The prediction accuracies are typically within + or - 1 dB for frequencies such that the line is electrically short (L 1/10 lambda) and + or - 6 dB for frequencies such that the line is electrically long (L 1/10 lambda). It was found that the parasitic wires in the cable can have a significant effect (as much as 40 dB for all frequencies) on the coupling between a generator circuit and a receptor circuit in the cable. Therefore to achieve accurate predictions in ribbon cables, one must consider the interactions between all wires in the cable. The wire insulation evidently can be ignored when the line is electrically short but cannot be ignored for higher frequencies. Conversely, the impedance of the reference wire cannot be ignored for low frequencies where the common impedance coupling dominates the electromagnetic field coupling. (Author)