Study of the Shielding Properties of Enclosures With Apertures at Higher Frequencies Using the Transmission-Line Modeling Method

The transmission-line modeling method and an analytical formulation are employed in this paper to investigate the electromagnetic shielding performance of enclosures with apertures. The effects of some related parameters, which are neglected in the formulation, are analyzed over a broad-band (0-3 GHz) to make the formulation optimal, and the shielding performance at some frequency points is studied in detail. Finally, approaches to improve shielding effectiveness are proposed. For the enclosures we studied, the theoretical analysis and simulation results illustrate that the analytical formulation can predict shielding effectiveness accurately when the frequency of the incident wave is less than 1 GHz, while when the frequency is more than 1 GHz, its applicability declines remarkably. Fortunately, the simulation results indicated that the shielding effectiveness can be improved to a certain extent by adjusting the spacing between apertures, selecting appropriate shapes of apertures, ensuring the longer side of apertures is not perpendicular to the polarization direction of the incident wave, and installing sensitive equipment according to the propagation direction in the case of that these properties of the incident wave are known.