Modeling external interference on systems using electromagnetic topology technique

External electromagnetic perturbations can be a hazardous threat to the safe performance of electrical systems used in communications or other sensitive applications. For simulations based on electromagnetic topology, we have developed a new methodology to determine the transfer function, through a small aperture, between an external source, induced by such disturbances, and the internal circuitry of a semi-shielded system. The simulation and analysis were performed using state of the art computer code which is based on the electromagnetic topology concept, having a cable network as its application domain. The results compare well with experiments. Analysis shows that the effects of the external fields on the cable current depend on the cable length, location, and terminating impedances.