A Modified Hybrid MoM-Modal Method for Shielding Effectiveness Evaluation of Rectangular Enclosures with Multiple Apertures

A new hybrid modal-moment method is proposed to calculate fields penetrated through small apertures on rectangular metallic enclosures. First, the method of moments is used to numerically solve the governing electric field integral equation for the equivalent two-dimensional surface-current distributions on the surface of metallic enclosure including any number of rectangular apertures of arbitrary lay-out. The resultant exterior scattered fields are then used as the input to a testing procedure to obtain aperture field distributions in the modal expansion technique. These fields can be directly transferred to interior penetrated fields, using appropriate Green’s function of the cavity inside region. To validate the method proposed in this paper, the results of the proposed method are compared with the measurement results available in the literature and those obtained using the conventional modal-moment method for both single and double aperture enclosures. It is shown that the proposed method offers a remarkable improvement in computation burden over the conventional method, especially for calculation of field penetration through much number of apertures typical to realistic measures in the discipline of electromagnetic compatibility.