Analysis of Shielding Effectiveness of a Cavity with Internal Dielectric Plate and Apertures

Focusing on the shielding effectiveness of a single-layer shielded cavity, especially the impact of aperture shape, aperture quantity, internal dielectric plate, and other factors on shielding effectiveness, an equivalent circuit model and BLT equation of shielding effectiveness for a single-layer shielded cavity under plane-wave irradiation were constructed by applying transmission line theory, Robinson's algorithm, and electromagnetic topology theory. The shielding effectiveness of the cavity with an internal dielectric plate subjected to 0 to 1 GHz electromagnetic waves was calculated. The influence of circular and rectangular aperture arrays, the thickness of the dielectric plate, and the position change of the dielectric plate on the electric field shielding effectiveness of the cavity were analyzed. HFSS was used for simulation experiments. The research indicates that increasing the number of apertures can effectively enhance the shielding effectiveness while keeping the total area of the apertures constant. In addition, the insertion of a dielectric plate inside the cavity, especially near the resonant frequency, significantly enhanced the shielding effectiveness due to the absorption of incident electromagnetic waves by the dielectric plate. As the thickness of the dielectric plate was increased, the resonant frequency of the cavity gradually decreased; the shielding effectiveness was improved near the resonant frequency. Placing the dielectric plate at the lower end of the cavity is preferred, as it significantly improves the shielding effectiveness.