Eliminate the guesswork from shielding enclosure design - The impact of apertures

The present article is concerned with a major aspect of shielding enclosure design, taking into account a metal or metallized plastic box with many apertures. It is pointed out that the leakages of the apertures compromise the shielding integrity of the metal/metallized box skin. The factors which limit the effectiveness of the shielding are examined. It is recognized that the specific location of a potentially susceptible circuit within a shielding enclosure does make a difference. However, in one approach for evaluating shielding characteristics, such a difference is disregarded for reasons of simplicity. Attention is given to additional shielding effectiveness in dB due to the cover panel shadow effect, leakages from multiple or subdivided apertures, effects of aperture gap depth, and convection cooling slots.