Analysis of Shielding Effectiveness of Rectangular Cavity with Improved Aperture Model

This article first introduces the improved theory of transmission line method (TLM), which is used to analyze shielding effectiveness of rectangular enclosure with improved aperture model. The calculations show that the contours of TML shielding efficiency is in agreement with the that of FDTD calculation. Then we expand the fundamental formulas to deal with the cases of multi-holes, and arbitrary angle of polarization. Simulation results indicate that: when the frequency is under resonant frequency, the closer to the enclosure, the more the coupling energy is; resonance appears between the aperture and the enclosure, which results in low even negative shielding effectiveness in the metal shell; shielding effectiveness increases when polarization angle increases, and shielding of low frequency is better than that of high frequency; for the same areas, shielding effectiveness of a single hole is worse than that of multi-one. Suggestions to the shielding are proposed.