EMI from cavity modes of shielding enclosures-FDTD modeling and measurements

TLDR

EMI can leak from slots and apertures in rectangular enclosures via coupling to interior cavity modes. The authors experimentally excited a specially designed test enclosure with slots or apertures and modeled the resulting EMI using finite‑difference time‑domain (FDTD) simulations. Measured and simulated results agree, showing that radiation through nonresonant slots or apertures at cavity‑mode frequencies can be as strong as at aperture resonances, validating FDTD as a useful tool for shielding design.

Abstract

Electromagnetic interference (EMI) from slots and apertures resulting from coupling of interior sources through enclosure cavity modes in a rectangular test enclosure is reported. EMI from a specially designed test enclosure with slots or apertures excited by interior sources was studied experimentally and with finite-difference time-domain (FDTD) modeling. The measurements and FDTD modeling agree well. The results indicate that radiation at cavity mode resonances through slots and apertures of nonresonant dimensions can be as significant as the radiation at aperture or slot resonances. The agreement between the FDTD modeling and measurements demonstrates the usefulness of FDTD for investigating aspects of shielding enclosure design such as coupling to slots and apertures and slot interactions.