Study of Shielding Properties of a Rectangular Enclosure with Apertures Having Different Shapes but Same Area Using Modal Method of Moments

In this study, electric field Shielding Effectiveness (SE) of rectangular enclosure with apertures illuminated by vertical polarization plane wave has been studied by using modal method of moment technique. Electric field SE of enclosure with different shape apertures but same area has been c alculated at three different points inside enclosure. To achieve this, assuming appropriate electric field distribution on the aperture, fields inside the cavity are determined using rectangular cavity Green’s function. Electromagnetic fields outside the cavity and scattered due to the aperture are obtained using the free space Green’s function. Matching the tangential magnetic field across the apertures, the integral equation with aperture fields as unknown variables is obtained. A very good agreement among the results of the proposed technique, results available in the literature and experimental results is observed. The simulation results show that the electric field SE is seriously affected by calculation points, aperture shape and the number of aperture. It has been shown that usual assumption made in EMC literature that lower electric field SE near the aperture than at location inside the enclosure farther away from the aperture is not always true to square aperture at some frequency and square aperture has higher electric field SE than rectangular aperture even though they have same area.