An EMI estimate for shielding-enclosure evaluation

A relatively simple, closed-form expression has been developed to estimate the EMI from shielding enclosures due to coupling from interior sources thr ough slots and apertures at enclosure cavity modes. A power-balance method, Bethe's small-hole theory, and empirically developed formulas for the rela tion between radiation, and slot length and number of slots, were employed to estimate an upper bound on the radiated EMI from shielding enclosures. C omparisons between measurements and estimated field strengths suitably agre e within engineering accuracy.