EMI from apertures at enclosure cavity mode resonances

EMI from slots and apertures resulting from coupling of interior sources through enclosure cavity modes in a Sun S-1000 workstation was investigated. The excitation of a specially designed rectangular enclosure with a slot was also studied experimentally and with finite-difference time-domain (FDTD) simulations. The radiated power results for both the S-1000 and simple rectangular enclosure indicate that radiation at cavity mode resonance frequencies through slots and apertures can be as significant as at aperture or slot resonances. A decrease of the radiation through the slots and apertures can be achieved by employing a lossy material in the enclosure.