Methodology for uncertainty management in EMC measurements

Electromagnetic compatibility (EMC) is undoubtedly a unique field, as it addresses risk avoidance but does not participate in product design in the same way as mechanics, electronics, etc. This risk stems mainly from unforeseen interactions between electronic systems. EMC is concerned with an area that is not considered by the designer; This highlights the growing importance of its analysis and the assessment of the uncertainties that characterize the scenarios and models required when studying the EMC of systems. The number of interactions between electronic systems quickly exceeds the imagination, and various difficulties arise in EMC and for EMC professions if the uncertainties inherent in systems are taken into account in detail. For example, some interactions are naturally random (e.g., discharge events, lightning phenomena, absolute knowledge of impedance levels in a system, etc.). In addition, these interactions can give rise to behaviors that would not exist in decoupled electronics. As a result, EMC has all the attributes of systems theory and deals with complex systems.

While certain standards and specifications provide a standard framework, advanced methods such as uncertainty propagation or Monte Carlo (MC) simulation are used for complex cases, mainly numerical (i.e., by simulation), as MC is ill-suited to the number of realizations required to apply to measurements (several thousand, tens of thousands, or even more, depending on the desired observables). Thus, while the MC method is resource-intensive, the development of reduced-order models and techniques based on metamodels makes it possible to optimize calculations. Uncertainty analysis becomes crucial for assessing risks, particularly in extreme cases. A preliminary theoretical analysis is essential to validate the models implemented to take into account the reality of EMC scenarios.

Finally, it should be noted that the most critical uncertainty concerns electronic systems, not electromagnetic fields themselves. EMC engineers constantly refer to a theoretical quantity that remains directly inaccessible through experimentation: the electromagnetic field. By constantly manipulating, citing, and calculating this intangible quantity, some may forget its fundamental properties; there is therefore a high risk that these multiple simplifications will distort the reality of this quantity and its use in electronic systems and protection measures. In this article, we will provide some of the basics necessary for understanding these uncertainties, while remaining strictly within the scientific scope of EMC.

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