Unified multiconductor transmission-line model of multiple-shields multiconductor cables: evaluation of shield connections performances

This paper presents a transmission-line model of a multiple-shields multiconductor cable. This unified model includes at the same time the propagation and cross-coupling characteristics of the electrical wires and of the cable-shields. It also includes the electromagnetic characteristics of the shields (in terms of transfer impedance and transfer admittance). It is derived in compliance with the multiconductor-transmission-line theory and it is valid whatever the connection configurations at the shield ends are. Therefore, it makes it possible the modelling of realistic connection problems ranging from ideal 360° shield connections to simple bonding wires. In addition, it is suitable for both electromagnetic susceptibility and emission problems. The paper proposes a physical explanation of the derived per-unit-length matrices. This unified model is also used to define the required conditions for being able to calculate the response of a shielded-cable in a two-steps model in which the shield problem and the inner shield problem are solved in sequence. Finally, the paper illustrates an application of the model in order to evaluate performances of a shielded-cable-link on crosstalk configurations with respect to various electrical bonding techniques of the shield.