Numerical Simulation And Optimization For EMI Suppression With Absorbing Materials

To meet the requirements of ventilation and heat dissipation, there always arises the need to adopt apertures in shielding enclosure of electronic equipment. In this way, the integrality of the shielding enclosure is destroyed. Aperture arrays for airflow in enclosure can become the coupling path of electromagnetic interference (EMI) from internal sources to external environment, especially around the resonant frequency of the enclosure, this coupling electromagnetic energy through apertures reached to the maximum and has exceeded the EMI limits within the range of some frequencies, this may result in EMI problems, thus decreased the shielding effectiveness of the shielding enclosure and the electromagnetic compatibility (EMC) of the system.Absorbing materials, which can absorb the electromagnetic waves, can be attached on the inner wall of the shielding enclosure to prevent electromagnetic leakage and minimize electromagnetic interference effectively. This paper mainly studies the influence of the shape, position, size, number and distance of the apertures in the enclosure on electromagnetic shielding effectiveness and its effects on the distribution of electromagnetic field. After the theory deduction and numerical simulation, different absorbing material with different size and position are studied to present its effect for EMI suppression. Finally, the model with absorbing material is optimized concerning both the demand of thermal design and EMC design, an optimization model for simple case is established and analyzed.