一种内置条状金属板的双层金属腔体屏蔽效能的理论模型

针对复杂屏蔽腔体往往是由多个空间构成的实际情况, 本文构建了内置条状金属板的双层金属腔体物理解析模型, 将外层腔体的近场电磁干扰等效为电偶极子, 基于Bethe小孔耦合理论并利用推广的腔体格林函数推导了内腔体的电磁场分布的近似表达式. 利用该解析模型计算分析了条状金属板的位置和方向对屏蔽效能的影响. 通过计算结果与全波仿真软件CST仿真结果的对比, 证实了本文所建理论模型的有效性, 为复杂腔体屏蔽效能的快速计算提供了理论参考.

An analytical model for shielding effectiveness of double layer rectangular enclosure with inner strip-shaped metallic plate

An analytical model for double-layer shielding metallic enclosure with inner strip-shaped metallic plates is proposed for analyzing the shielding effectiveness of complex enclosures containing multiple spatial structures, based on the actual situation that the circuit systems in each spatial region are inevitably interfered by the electromagnetic penetration of those in adjacent spatial regions through slots, cables, and other transmission channels. The near-field electromagnetic interference of the external layer of the enclosure is represented by the equivalent electric dipoles, and the internal layer of it is regarded as the target point of shielding effectiveness, the analytical formulas of the internal layer's electromagnetic field then are derived based on Bethe's small aperture coupling theory and generalized Green's function. The model is employed to analyze the influences of some parameters of the strip-shaped metallic plate on the shielding effectiveness. It is shown that the position and direction of the strip-shaped metallic plate have obvious influence on the shielding effectiveness of the target point of the internal layer, embodied by the shielding values over some frequency ranges and different resonant modes, and at the same time the corresponding physical mechanisms are also given in detail. Comparison with the full wave simulation software CST has verified the model over a very broad frequency range, which provides a theoretical reference for the rapid calculation for shielding effectiveness of complex enclosures.