Use of Huygens source excitation in a MoM surface-current EFIE formulation

In this paper the equivalence theorem (Huygens principle) is applied in conjunction with a method of moments (MoM) surface current formulation in order to improve the computation of a certain class of problems arising in the area of EMC. Of special interest is the effect of holes and slots upon the forming of the interior fields of enclosures. For an effective aperture treatment based on a MoM EFIE formulation the electric MoM currents and the electric equivalent sources (Huygens sources) have to be galvanically connected in order to satisfy the continuity equation at the interface. It is observed that one can circumvent instabilities of the EFIE at resonances leading to false interior fields by replacing the original excitation by Huygens sources in the aperture. In a first standard MoM computation the current distribution of the structure is gained. Then the original excitation is replaced by Huygens currents in the aperture plane. A second MoM computation is necessary to compute the internal current distribution. Such a step-by-step EFIE procedure is computationally more efficient than a double-layer current approach. The numerical effort is reduced by almost a factor of four.