Two Advanced Types of Air Vent for Improved EMI Shielding and Air Flow

Air-vents on a system chassis are designed to allow efficient air flow to cool the system, while at the same time shield unwanted electromagnetic energy. With the speed and power consumption of systems increasing with new product generation, striking a balance between reducing EMI and meeting thermal requirements has become more challenging. This paper investigated two novel types of air vent for better shielding effectiveness (SE) and air flow performance. First one is air vent with openings of random size and location, dozens of cases were simulated and demonstrate that there exist some random cases which have better SE in certain frequency range without impacting on air flow performance. The other one is called air vent with non-uniform cross section, based on the Bernoulli’s principle, several cases of air vent with different non-uniform cross section types were modeled, and both simulation data and measurement results show the improvement in EMI shielding effectiveness and pressure drop of air flow.