Coupling Analysis of Shielded and Unshielded Star Quad Cables Excited by an Intentional Electromagnetic Pulse

Coupling analysis of shielded and unshielded star quad cables excited by an intentional electromagnetic pulse (IEMP) is investigated using the transmission line theory-based perturbation technique. A detailed modal analysis is presented to obtain the modal per-unit-length parameters of the modal signals in such shielded/unshielded star quad cables. Due to their geometrical balanced structures, with opposite wires used for +leg and −leg to transfer the differential-mode (DM) signal, the external coupling is dramatically suppressed. Moreover, stochastic analyses based on the Monte Carlo simulation are also performed to study the sensitivity of the induced common-mode (CM) and DM currents, due to the deformation effects of the twisting structure of the cable. It is found that the induced CM and DM currents are slightly affected by the twisting deformation of the cable because the interference cancelations do not mainly depend on the twisting loops of the cable. In particular, time domain analysis is performed to study the field-to-wire coupling of the star quad cables exposed to an IEMP, where the worst-case waveform signals in the presence of an IEMP attack are captured and analyzed.