Shielding effectiveness of enclosure with unconventional aperture array

The transmission-line modeling (TLM) numerical method is employed to investigate the high-frequency shielding effectiveness (SE) of a metallic enclosure with unconventional aperture geometries. Analytical methods can predict SE but they have two main limitations: one is they can predict the SE of enclosure with very simple aperture shapes and second is that results cannot be predicted with accuracy after the first resonance frequency of cavity. We have investigated some new geometries for apertures from 0 to 3 GHz frequency band and discovered some important characteristics of these shapes by using the TLM based simulator. A novel concept of complementary apertures is introduced which has pronounced effect on cavity resonance modes and SE of enclosure. Another useful phenomenon was also observed and that is despite of longer aperture lengths perpendicular to electrical field (E-field), some apertures have better SE than others for the same coverage area.