Characterization of a cylindrical screen for external excitations and application to shielded cables

The main purpose of this paper is to present the definition of sets of parameters, which provide an intrinsic characterization of the shielding performances of a cylindrical generalized screen submitted to an external field. As examples, we detail two implementations of this approach, for the computation of the voltages induced by an incident field on a short section of a multiconductor shielded cable. More precisely, our approach is based on an expansion of the fields which may excite the generalized screen, into a combination of "standard excitations." They are defined in such a way that the shielding performances for a given standard excitation can be characterized in a simple manner, for instance, a single scalar parameter. In the case of shielded cables of electrically small cross section, this leads us to the rigorous introduction of the parameters for the "five main types of coupling," for which some experimental results have already been published. We then establish the exact induced current and voltage on a section of cable running above a ground plane, when an incident field propagates parallel to the ground plane, in the case of a longitudinal excitation, and in the case of a transverse excitation. We use these results to provide the value of the voltages at each end of a short section of cable characterized with the parameters for the five main types of coupling.