In this paper, a network of ports will be used to optimize the locations and geometries for apertures on a metallic enclosure. S-parameter analysis and circuit theory approach are essential in description of the shielding effectiveness in this method. An analytic discussion is employed to show the correctness of the new method and a case study with this port network is implemented to show the consistency of the results with previous researches. The proposed approach does not have the limitations of the traditional simulation and experimental methods such as dimension limits and the need for antennas, shielded rooms, etc.

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