Coupling to devices in electrically large cavities, or why classical EMC evaluation techniques are becoming obsolete

We show that the coupling between a sensor in an electrically large metallic cavity (artifact) and the outside world is a very complicated problem, with small changes inside the cavity resulting in signal changes of greater than 20 dB. However, this problem can be greatly simplified by separating the task into two components: a statistical "reverberation chamber" type component, and a deterministic component (trends as a function of aspect angle, frequency, or other parameter). We give methods for evaluating each of these effects, and show how they can be applied in a specific detailed example.