传输线理论在屏蔽防护中的应用

发布时间：2018-05-02 03:41

本文选题：传输线理论 + 屏蔽效能　；参考：《西安电子科技大学》2014年硕士论文

【摘要】：随着电子技术越来越朝着高频率、高速度、高灵敏度、高可靠性以及多功能小型化的方向发展,导致了现代电子设备产生和接受电磁干扰的几率大大增加"电磁兼容一般指电气及电子设备在共同的电磁环境中能执行各自功能的共存状态,是设备和系统的重要质量指标,也是保障系统工作效能和提高系统可靠性的重要因数,普遍受到各国工业界、研究机构的高度重视,被各国确认为电子产品的强制认论证重要组成部分。屏蔽被认为解决电磁兼容问题主要三大手段之一,而备受关注。在电子设备和系统的电磁兼容设计中,金属导体屏蔽是一项非常重要的技术。对于许多电子产品而言,如果没有屏蔽措施,很难满足其电磁兼容要求。然而,由于设备散热、通风以及与外界电路连接等的需要,屏蔽导体上不可避免地存在着孔缝,而孔缝的存在是影响系统屏蔽性能的关键因素。因此,充分了解金属导体上孔缝对电磁波的散射、透射及耦合机理,对于电子电气设备和系统的电磁兼容性预测和设计,具有十分重要的实际指导意义。本文运用等效传输线法,对开孔为单孔、孔阵以及双层屏蔽体结构的矩形金属屏蔽腔体的电磁屏蔽效能进行了评价和分析,并运用Matlab进行了仿真计算。具体内容如下:首先对M.P.Robinson等人提出的有孔矩形腔传输线模型的基本理论进行介绍并对计算有孔矩形腔屏蔽效能的计算公式进行推导。针对模型中未考虑的入射平面波极化方向的问题,在此基础上完整分析和推导了入射平面波为任意极化方向的条件下,屏蔽腔体的屏蔽效能计算公式。通过解析计算分析了孔缝大小、开孔形状、孔阵中孔间距以及外部入射电磁波的极化方向等因素对腔体屏蔽效能的影响,总结了多项屏蔽腔体加固设计技术的结论。然后进一步推广研究了双层金属屏蔽腔的屏蔽效能,建立了双层金属屏蔽腔的等效电路模型,推导出了快速计算双层金属腔体屏蔽效能的解析表达式,同时研究了内孔位置等对屏蔽效能的影响。
[Abstract]:With the increasing trend of electronic technology towards high frequency, high speed, high sensitivity, high reliability and multifunction miniaturization, the probability of modern electronic devices to produce and accept electromagnetic interference is greatly increased. "EMC generally refers to the coexistence of electrical and electronic devices in the common electromagnetic environment." It is an important quality index of equipment and system. It is also an important factor to ensure the efficiency of the system and improve the reliability of the system. It is highly valued by the industry and research institutions of all countries. It is recognized by all countries as an important part of the compulsory identification of electronic products. It is one of the three major means to shield the problem of electromagnetic compatibility. The shielding of metal conductors is a very important technology in the electromagnetic compatibility design of electronic devices and systems. For many electronic products, it is difficult to meet their electromagnetic compatibility requirements without shielding measures. However, the shielding conductors can not be shielded due to the need of equipment for heat dissipation, ventilation, and the connection with the external circuit. The existence of the holes is the key factor affecting the shielding performance of the system. Therefore, it is very important to understand the scattering, transmission and coupling mechanism of the holes on the metal conductor, which is of great practical significance to the electromagnetic compatibility prediction and design of the electronic and electrical equipment and the system. The transmission line method is used to evaluate and analyze the electromagnetic shielding effectiveness of a rectangular metal shielding cavity with a single hole as a single hole, a hole array and a double-layer shield. The simulation calculation is carried out with Matlab. The contents are as follows: first, the basic theory of the rectangular cavity transmission line model proposed by M.P.Robinson and others is introduced and calculated. A formula for calculating the shielding effectiveness of a rectangular cavity is derived. On the basis of the problem of the polarization direction of the incident plane wave, which is not considered in the model, the shielding effectiveness calculation formula of the shielding cavity is completely analyzed and deduced on the basis of the incident plane wave as an arbitrary polarization direction. The size of the hole and the shape of the opening are analyzed and calculated by analytical calculation. The influence of the spacing of holes in the hole and the polarization direction of the external incident electromagnetic wave on the shielding effectiveness of the cavity has been summarized. Then the shielding effectiveness of the shielding cavity is summarized. Then the shielding effectiveness of the double-layer metal shielding cavity is further extended and the equivalent circuit model of the double-layer metal shielding cavity is established, and the rapid calculation is derived. The analytical expression of shielding effectiveness of a double-layer metal cavity is studied, and the influence of the location of the inner hole on shielding effectiveness is also studied.

【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN03;TN811

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