A relatively simple, closed-form expression has been developed to estimate the EMI from shielding enclosures due to coupling from interior sources through slots and apertures at the enclosure cavity modes. A power-balance method, Bethe's (1944) small-hole theory, and empirically developed formulas for the relation between radiation, and slot length and number of slots, were employed to estimate an upper bound on the radiated EMI from shielding enclosures. Comparisons between measurements and estimated field strengths suitably agree within engineering accuracy.


Electrical and Computer Engineering

Research Center/Lab(s)

Electromagnetic Compatibility (EMC) Laboratory

Keywords and Phrases

Bethe's Small-Hole Theory; EM Coupling; EM Diffraction; EMC; EMI Estimate; Apertures; Cavity Resonators; Cavity-Mode Resonances; Closed-Form Expression; Electromagnetic Coupling; Electromagnetic Interference; Electromagnetic Shielding; Electromagnetic Wave Diffraction; Enclosure Cavity Modes; Engineering Accuracy; Estimated Field Strengths; Interior Sources; Measurements; Power-Balance Method; Radiated EMI; Radiation; Shielding Enclosures; Slot Length; Slots; Upper Bound; Apertures; Cavities; Diffraction; Electrical Equipment Enclosures; Shielding

International Standard Serial Number (ISSN)

0018-9375; 1558-187X

Document Type

Article - Journal

Document Version

Final Version

File Type





© 2001 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

Publication Date

01 Aug 2001