复杂金属腔体的屏蔽效能分析与天线耦合特性研究-电磁场与微波技术专业论文.docxVIP

第 第 - 1 - 页 第 第 - 2 - 页 STUDY ON SHIELDING EFFECTIVENESS OF COMPLEX METALLIC ENCLOSURES AND ANTENNA COUPLING CHARACTERISTICS ABSTRACT Electromagnetic pulse (EMP) is an electromagnetic phenomena with high electric field intensity and quite quite short rise time. It carries much engry that can cause serious EMI problem to the communication systems. Metal shielding structures are often used to protect electronic equipment from the radiation of electromagnetic pulse (EMP). However, some apertures have to be introduced on the cavity walls. In Chapter 2 of the thesis, shielding theory is reviewed at first, together with different waveforms of EMPs outlined and the definition of shielding effectiveness given. In Chapter 3, the shielding effectiveness of cylindrical cavities with different slots is investigated numerically with commercial software used. It is found that the shielding effectiveness is reduced significantly at the self-resonant frequencies of the cylindrical cavity. And evidently, the orientation and number of slots have strong effect on the inner field distribution. In Chapter 4, the shielding effectiveness of ladder-shaped metallic cavity is further investigated numerically, and in particular, the technique of window function is implemented in the shielding analysis. In Chapter 5, the coupling characteristies between double antenna elements are examined, which is useful for wireless communication. In particular, the effects of human head on the radiated field are studied, with some useful conclusions drawn finally. Key words: Electromagnetic Pulse (EMP), Shielding Effectiveness, Aperture Coupling, Antenna, Near-field Radiation. 目 录 摘 要 - 1 - ABSTRACT - 1 - 第一章 绪 论 3 1.1 研究背景及意义 3 1.2 研究问题进展 4 1.2.1 屏蔽效能 4 1.2.2 天线互耦 5 1.3 本文主要研究内容 5 第二章 电磁屏蔽的基本理论7 2.1 电磁屏蔽的基本概念 7 2.2 电磁脉冲的耦合途径 8 2.3 典型电磁脉冲 9 2.3.1 双指数脉冲 9 2.3.2 调制高斯脉冲 11 2.3.3 超宽带脉冲 14 2.4 屏蔽效能定义 15 2.5 本章小结 16 第三章 圆柱形屏蔽腔体的屏蔽效能分析17 3.1 数值验证 17 3.2 矩形细缝不同取向的屏蔽效能分析 20 3.2.1 横向开缝情况 20