Abnormal phenomenon on shielding effectiveness of metallic enclosures with one aperture at normal and oblique incidences

Abnormal phenomenon on shielding effectiveness (SE) of metallic enclosures with one rectangular aperture when illuminated by the oblique and normal incidence vertical polarized plane wave has been studied by using MoM and FIT techniques. To the best knowledge of authors, the similar phenomenon and analysis for it has not been investigated. The work shown that the usual assumption about the normal incidence being the worst-case scenario for shielding effectiveness values may not be valid when there is even only one aperture in the cavity. In addition, the SE of normal incidence is perfectly able to exceeds that of oblique incidence. The paper emphasizes the extension of the existing cognition of shielding effectiveness problem of metallic enclosures with apertures about oblique and normal incidence.