非接触搭接结构电磁屏蔽特性的数值分析

Numerical analysis on the electromagnetic shielding properties of non-contact overlapped joints

非接触搭接是电子设备箱体常见的连接形式,搭接处会不可避免地存在缝隙,而缝隙是电磁泄漏的主要途径,将致使箱体屏蔽效能降低,故有必要探索增强腔体屏蔽效能的方法.以几种典型非接触搭接金属箱体为研究对象,在平面波激励下,利用传输线矩阵法(TLM)和波导理论,对搭接长度、缝隙宽度、缝隙长度等参数对箱体屏效的影响进行了定量的数值计算和定性的理论分析,结论表明通过减小缝隙宽度、增加搭接长度和螺钉分段均可提高箱体屏效.同时计算分析了不同搭接形式对箱体屏效的影响,提出了能够实现高屏效的搭接结构途径,并结合矩形波导理论得到采用弯折搭接结构也能够显著提高箱体屏效的结论.研究结果可为电子设备的电磁屏蔽设计提供依据.

Non-contact overlapped joint is a frequently used connection structure in enclosure of e- lectronic equipment. Slots are inevitably present in this structure, which result in leakage of elec- tromagnetic energy and deteriorates of shielding effectiveness, so it is necessary to explore meth- ods to enhance the shielding effectiveness of non-contact overlapped joints. The shielding per- formances of several metallic enclosures with typical non-contact overlaps motivated by plane wave were investigated. Moreover, parameters of overlapped slots such as overlapped length, width, height, and number of segments divided by screws were investigated by the transmission- line matrix （TLM） method and waveguide theory. Based on quantitative calculation and qualita- tive analysis, the results indicate that the shielding effectiveness can be improved to a certain ex- tent by reducing the width of slots, increasing the length of overlaps and the number of screws. At the same time, non-contact overlapped joint structures which can provide high shielding effec- tiveness are proposed based on analysis and comparison. Then combined with the rectangular waveguide transmission theory, we come to the conclusion that adopting bending overlapped structure is another contributing factor to improve the shielding effectiveness. The conclusions have been demonstrated to be helpful guidance for shielding enclosure design.