Knowledge of the shielding effectiveness (SE) of an enclosure is important for the electromagnetic compatibility of electronic systems. The SE of an enclosure depends on the absorption cross section (ACS) of its contents, the circuit cards, disk drives etc. In most published work, the ACS measurements were performed when the contents were unpowered. We expected that the ACS would be different when a circuit is powered as many of the active devices would be biased into conduction. Also we have observed in previous work that the switching activity causes a circuit to act as a modulated scatterer. In this work we compare the measured ACS of the contents of a PC in powered and unpowered state.
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|Published - 1 Jun 2016