Meaning
Radiated energy escaping through visual displays, buttons or connector ports reduces the overall shielding effectiveness of a hardware device. If enclosure aperture leakage is not controlled, the internal signals of a fast processor might interfere with external radio networks or nearby electronic devices. It is a function of the slot size relative to the wavelength of the highest frequency present inside the housing.
Shielding Effectiveness
Small openings act like unintended antennas when their dimensions approach half the wavelength of a harmonic signal. Minimizing enclosure aperture leakage requires limiting the length of any single continuous gap in the metal shell. Metal mesh or specialized conductive films across screen windows help contain the energy.
Geometric Attenuation
Depth to width ratios of every hole in the box influence how much energy survives the passage from inside to outside. When enclosure aperture leakage occurs at a specific frequency, redesigning the slot shape provides a mechanical solution to the resonance problem. Wide shallow gaps are much more prone to emissions than round deep holes.
Frequency Dependency
High gigahertz signals find gaps that would be invisible to lower megahertz waves. Proper evaluation of enclosure aperture leakage involves testing the module in various orientations to see which port radiates the most. Correcting these leaks is the most common path to passing formal regulatory tests.
