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).

Random cable bundles as described in this report are groups of wires (cylindrical conductors) in which the relative wire positions are unknown and vary in some uncontrolled fashion along the cable length. These cable bundles result from the need to contain wires connecting electronic equipments in compact groups. Current practice in the avionics industry is to group wires into these random bundles although the use of ribbon cables (in which wire position is carefully controlled) is increasing. These random bundles can be quite large and no attempt is made to control the relative wire positions within the bundle. Wire-coupled interference (crosstalk) in cable bundles results from the unintentional coupling of signals from one circuit into another by virtue of the electromagnetic interaction between wires in the same cable bundle. The ability to predict this crosstalk is obviously quite important in determining overall system compatibility, i.e., will the system performance by degraded to an intolerable level by this interference.

The essential textbook for electrical engineering students and professionals-now in a valuable new edition The increasing use of high-speed digital technology requires that all electrical engineers have a working knowledge of transmission lines. However, because of the introduction of computer engineering courses into already-crowded four-year undergraduate programs, the transmission line courses in many electrical engineering programs have been relegated to a senior technical elective, if offered at all. Now, Analysis of Multiconductor Transmission Lines, Second Edition has been significantly updated and reorganized to fill the need for a structured course on transmission lines in a senior undergraduate- or graduate-level electrical engineering program. In this new edition, each broad analysis topic, e.g., per-unit-length parameters, frequency-domain analysis, time-domain analysis, and incident field excitation, now has a chapter concerning two-conductor lines followed immediately by a chapter on MTLs for that topic. This enables instructors to emphasize two-conductor lines or MTLs or both. In addition to the reorganization of the material, this Second Edition now contains important advancements in analysis methods that have developed since the previous edition, such as methods for achieving signal integrity (SI) in high-speed digital interconnects, the finite-difference, time-domain (FDTD) solution methods, and the time-domain to frequency-domain transformation (TDFD) method. Furthermore, the content of Chapters 8 and 9 on digital signal propagation and signal integrity application has been considerably expanded upon to reflect all of the vital information current and future designers of high-speed digital systems need to know. Complete with an accompanying FTP site, appendices with descriptions of numerous FORTRAN computer codes that implement all the techniques in the text, and a brief but thorough tutorial on the SPICE/PSPICE circuit analysis program, Analysis of Multiconductor Transmission Lines, Second Edition is an indispensable textbook for students and a valuable resource for industry professionals.

The contents of this report are concerned with the electromagnetic coupling (crosstalk) between braided-shield cables. The effect of pigtails (exposed sections of braided-shield cables in which the shield is stripped back exposing the interior wire) on crosstalk was investigated. It was found that even though the length of these exposed sections constitutes only a very small fraction of the total line length the dominant coupling to the shielded cable can occur via these pigtail sections. If the pigtail sections are eliminated, an additional reduction in crosstalk of as much as 30dB may be realized. The modeling and prediction of this crosstalk was also investigated. A low-frequency model provided accurate predictions for electrically short lines. The multiconductor transmission line (MTL) model was also formulated. The MTL model provided predictions within 1-3dB for electrically short lines and within 6-10dB when the line was electrically long.

The report is the first volume in a series of reports documenting the Application of Multiconductor Transmission Line Theory to the Prediction of Cable Coupling. Modern avionics systems are becoming increasingly complex. These systems generally contain large numbers of wires connecting the various electronic equipments. The majority of the wires are in very close proximity to each other in either random cable bundles (in which the relative wire positions are not known or controlled) or in ribbon cables (in which the relative wire positions are known and controlled). The prediction of wire-doupled Interference in these cable bundles is of considerable importance in the prediction of overall system compatibility. It is the purpose fo this series of reports to examine the application of multiconductor transmission line theory to this problem. The first volume is intended to provide a comprehensive discussion of multiconductor transmission line theory on which the remaining volumes will be based. The remaining volumes will investigate the application of this theory to specific classes of problems.

A transmission line model of the twisted wire pair is presented which may be used to compute electromagnetic coupling between the twisted wire pair and other circuits. The model is derived by representing the transmission line for the twisted wire pair as a cascade of uniform loops and 'abruptly' nonuniform twists. The overall transmission line matrix is found by cascading the chain parameter matrices, which represent the loops, with the permutation matrices, that represent the twists. Comparisons are presented between the twisted wire pair, the straight wire pair, and the single wire circuit configurations to determine the relative effectiveness in the reduction of electromagnetic coupling. Experimental results are compared to the model predictions which verify that the chain parameter model is accurate to within + or - 3 dB for frequencies such that the line is electrically short (i. e. 1/10 lambda). Finally a second model, the low frequency model, is presented and is shown to be as accurate as the chain parameter model in the prediction of coupling at low frequencies. This low frequency model is very appealing in that it is conceptually much easier to model and also less time consuming, computationally.