This letter shows a method for approximately calculating the shielding effe
ctiveness of a rectangular enclosure with thick multiple apertures. Numeric
al results illustrate the shielding effectiveness of the enclosure with var
ious thicknesses and aperture spacings. This method is reasonably accurate
up to 2 / 3 of the cutoff frequency associated with the longer aperture dim
ension. (C) 2001 John Wiley & Sons. Inc.