Different numerical methods for electromagnetic field computation with thin shielding sheets

The disturbance of sensitive measurement and control equipment by electromagnetic fields is a central problem in electromagnetic compatibility. A removal or reduction of such a disturbance is achieved by thin shielding sheets, the optimum design of which nowadays can be found by numerical methods. This paper describes the principles of three new methods for this task. The first method is the conventional hybrid FEM/BEM-method, which analyzes a 3D distribution of the fields numerically in the interior of the shielding sheet as well as in its surroundings. In the case of linear shielding material the 3D discretization can be replaced by a 2D one on the shielding sheet surface in the second and third method. While the second method leads to a more appropriate FEM/BEM formulation for thin shielding sheets than the first one, the third one has the advantage that only a BEM formulation is needed to solve the problem. Some EMC applications and their results illustrate the use of the methods.