INTEGRAL EQUATION METHOD FOR LIGHTNING INDIRECT EFFECTS AND HIRF APPLICATIONS

摘要

Integral equation method also known as BEM (Boundary Element Method) or MoM (Method of Moments) is widely used in industry for the resolution of Maxwell's equations for medium to high frequency applications. Despite its many qualities, this method is not much used for EMC applications including Lightning Indirect Effects (LIE) and High-Intensity Radiated Fields (HIRF). In fact, low frequency limit is singular which induces numerical instability of the discrete system. This instability can be tackled by using loop-tree decomposition. Unfortunately it is notoriously difficult to extend this decomposition to multi-domain problems. Another known issue is the difficulty of computing very low levels of fields and currents inside cavities since they are computed as the difference between two quantities of similar amplitude. In this paper, we propose a new formulation that overcomes these difficulties. It is based on a domain decomposition approach with unknown currents associated to each domain. E and H fields inside each domain are represented by the equivalent currents on its boundary: thus, arbitrary low level fields are accurately computed. Low frequency stability is ensured independently in each domain by loop-tree decomposition. In addition, the coupling between domains handles arbitrary transmission properties: transparent, resistive, conducting with skin effect or opaque. We will present some LIE and HIRF applications on simple geometries with comparison with FDTD or analytical solutions.