Modal Analysis for Induced Currents in Metallic Plates

Several electromagnetic systems and devices comprise metallic plates, acting either as structural support to other active parts of the system or as electromagnetic shield. In the case of external anomalous or unwanted electromagnetic solicitations, the plates are interested by induced currents. These currents couple with electrically active parts of the system generating spurious effects. To correctly size the protection circuits, the computation of reaction fields and the coupling with the structures is usually done numerically. In this study, we propose a modal analysis of the plate current map to achieve a semi-analytical expression, and we attempt to relate plate modes to a suitable set of lumped elements; this allows a straightforward integration with an equivalent circuit of the system active parts and a consequent ease of calculation for the sizing of the protection system. The results indicate that the proposed approach can achieve acceptable outcomes compared to the FEM approach. Achieving the desired outcomes depends on selecting an appropriate discretization step, which is influenced by both the number of modes and the frequency.