Analytical formulation for the shielding effectiveness of enclosures with apertures

An analytical formulation has been developed for the shielding effectiveness of a rectangular enclosure with an aperture. Both the magnetic and electric shielding may be calculated as a function of frequency, enclosure dimensions, aperture dimensions and position within the enclosure. Theoretical values of shielding effectiveness are in good agreement with measurements. The theory has been extended to account for circular apertures, multiple apertures, and the effect of the enclosure contents. The captions for Figures 12-16 were incorrect in the original published version. The captions should be: 12. Emissions measurement of shielding at centre of 300x120x300 mm enclosure with 150x40 mm aperture compared to calculated SE and SM. 13. Effect of loss term zeta on calculated SE. 14. Measured SE with various sized blocks of RAM in enclosure. 15. Measured SE with two different circuit boards in enclosure. 16. Measured and calculated SE at centre of 300 x 120 x 300mm enclosure with 88mm diameter circular aperture.