Modelling Interactions between Multiport-systems and Canonical Stochastic Environments

The interaction between an interconnect system and an electromagnetically active environment is one of the principal concerns in EMC modelling. An interconnect system can be modelled as a multi-port system and all its model parameters can be expressed in terms of integrals over system-bound current distributions and incident electromagnetic fields. These model parameters are the observables of the interaction theory. The difficulty we have to face is that we do not master the environment in every detail and if we want to make useful predictions of levels of environment induced interference, we shall have to quantify the fluctuations around our idealised or “average value” predictions. In this contribution, we define a canonical stochastic environment which can be seen as the most natural choice of ambient field given the knowledge we have about the configuration our system is going to be placed in. This leads to the computation of “interaction resistances,” to be added to the ports, which represent the energetic coupling to the environment. But, even more importantly, these resistances have a computable “noise temperature” expressed in terms of a single parameter characterising the level of the ambient electromagnetic field.