Network Model of Shielded Cables for the Analysis of Conducted Immunity and Emissions

In this paper, a network model for a shielded coaxial cable with a single braid placed above a ground plane is presented. The model is developed on a SPICE basis, taking into account the coupling from the outer system between the screen and the ground to the inner system between the core and the screen, and vice versa. The model enables determining the common-mode current on the cable shield. It considers the boundary conditions at the cable ends and can thus be integrated into circuits for conducted immunity and emission simulation. An immunity test can be simulated by applying a disturbance voltage or current to the shielding ends. The model can be used in the time domain along with non-linear elements or in the frequency domain. The cable is not divided into segments, and no inverse Fourier transform is applied. The results of the model are in good agreement with those of the measurements and the numerical simulations.