浅谈电磁兼容原理在电线电缆中的应用

随着电磁环境的日益恶化,电子元器件对电磁兼容的要求也越来越高。如何提高电线电缆的电磁屏蔽效果,减小电磁干扰也越来越受到电线电缆行业的关注。为此主要对电磁波、电磁干扰、屏蔽机理、屏蔽设计、屏蔽材料等内容进行了探讨。     

电子控制系统的屏蔽设计研究与应用

本文从电子控制系统电磁干扰源能量的"场"入手,分析了电子控制系统电磁干扰的多种形式,针对不同电子控制系统的电磁干扰类型,提出其解决办法与对策.并通过静电屏蔽、磁屏蔽、电磁屏蔽设计介绍了电子控制系统的屏蔽设计思路、方法与技巧.     

电磁屏蔽镀层的研究

本文主要介绍了电磁屏蔽（EMS）的基本原理和简单的电磁屏蔽知识,概述了电镀法在工程塑料上制备电磁屏蔽镀层的现状和进展,为解决电磁干扰（EMI）问题和进一步研究电磁屏蔽材料提供相关资料。     

电磁屏蔽材料（四）

4常用电磁屏蔽材料和元器件 电磁屏蔽是抑制电磁干扰的主要技术，电磁屏蔽材料和元器件日益引起世界各国的高度重视，纷纷投入大量的人力和物力进行深入研究。目前，发达国家，特别是美国、日本、俄罗斯等国已经形成生产各种类别和系列规格的电磁屏蔽材料和元器件产业。常用的电磁屏蔽材料和元器件主要可分为以下几类：     

显控机柜电磁屏蔽分析

以某系统显控机柜为例,就其可能存在的电磁干扰耦合途径展开讨论,分析各种结构设计的利弊,探讨较理想的屏蔽设计方法.     

电磁屏蔽材料的种类及应用

本文对电磁屏蔽材料（包括新材料、新品种）作了较全面的介绍，针对控制电器面临的日益严重的高频电磁干扰，以及ＥＭＣ设计中容易怒视的孔隙处理，特别介绍复合型高频电磁屏蔽材料及其应用。     

产品骚扰的的抑制方法

电子、电气产品之普及,已成为生活中不可缺少的一部分,伴随着而来的电磁干扰也越来越严重.文章介绍了EMC的规律,围绕电磁干扰的三要素,即电磁干扰源、电磁干扰的 传播途径和敏感设备,分析并讨论了抑制干扰的三大基本技术.即滤波、屏蔽、接地.     

吸波材料研究现状以及多层吸波材料反射损失计算

随着科学技术的不断进步,电气电子设备已经普及到社会的各个角落,电磁干扰(EMI)问题越来越突出,电子设备的电磁兼容已经被广泛关注。电磁屏蔽作为抑制电磁干扰的一个重要手段,在绝大多数的电子设备中得以应用。吸波材料对电磁波有吸收作用,可以用来克服反射式屏蔽的不足。本文首先介绍了吸波材料的吸波机理,对当今研究的纳米吸波材料进行了描述,最后给出了多层吸波材料反射损失的计算方法。     

导电衬垫在电磁屏蔽中的应用

分析屏蔽体抑制电磁干扰失败的原因，指出导电衬垫在抑制电磁干扰中的使用与作用。介绍金属螺旋管、导电橡胶、金属丝网、指形簧片和导电布等五种常用导电衬垫的材料组成、性能和适用范围，探讨其选择和安装问题。     

屏蔽在高压大电流环境中抑制电磁干扰的应用

屏蔽是抑制电磁干扰的一种主要方法，它对提高电子设备工作可靠性有着十分重要的作用。针对延时电路高压大电流的电磁兼容问题，通过对实际工作电路的测试和比较，分析了延时电路的电磁干扰及屏蔽技术在抑制高压大电流回路电磁干扰中的作用，初步得到了抑制电磁干扰的屏蔽措施，并证明了该屏蔽措施对抑制高压大电流放电干扰的有效性。     

Shielding effectiveness measurements of materials using nested reverberation chambers

The use of reverberation chambers for determining the shielding effectiveness has the advantage over other techniques in that the reverberation chamber exposes the material to a more realistic environment. That is, in a reverberation chamber, the fields are incident on the material with various polarizations and angles of incidence. There are various reverberation chamber techniques found in the literature and international standards. These techniques can give incorrect results because aperture and cavity-size effects are not correctly accounted for. In fact, we show that for no sample in the aperture, these techniques give a nonzero result for shielding effectiveness. In this paper, we review existing techniques and present a new technique for determining the shielding effectiveness of materials from nested reverberation-chamber measurements. The new approach accounts for aperture, cavity size, and chamber loading effects. Various examples are presented to illustrate the utility of the new approach, and a discussion on edge treatments of the materials is given.     

Low-Frequency Shielding Resonance

A low-frequency resonance in the 5- to 200-kHz range has been discovered in typical shielding enclosures. It is due to unequal phase shifts in wave transmission to a receiving point via two or more parallel paths: one through the shielding material itself and others through leakage paths such as seams. Theoretical and experimental results are shown to be in close agreement and indicate a new approach to the design of shielding enclosures.     

基于箱体法材料电磁脉冲场屏蔽效能测试研究

为准确评价屏蔽材料在强电磁脉冲环境中的屏蔽效能,提出了一种基于屏蔽暗箱窗口法的材料电磁脉冲屏蔽效能时域测量方法。该方法将带有测试窗口的屏蔽箱体置于GTEM 室内,被测屏蔽材料安装在屏蔽箱的测试窗口上,利用置于腔体中心的单极子天线测量耦合进腔体的电磁脉冲电压波形,对测得的时域电压信号进行快速傅里叶变换( FFT) ,得到了被测材料频域屏蔽效能曲线。与频域测试结果进行了对比,结果基本一致。实验表明该测试系统可以有效减小局部增强效应对测量精度的影响,能够可靠评价强电磁脉冲作用下材料的屏蔽效能。     

手征球壳的低频电磁屏蔽效应分析

分析了手征介质球壳的低频电磁屏蔽效应，给出了一组手征电磁屏蔽球壳的设计曲线。比较了手征材料的一般电、磁屏蔽材料的不同之处，重点说明了该材料的特殊性。理论计算表明，这种新型材料是一种非常有前途的电磁屏蔽材料。     

A simple hybrid method for ELF shielding by imperfect finite planar shields

A simple method is described for calculating the shielding performance of a two-dimensional (2-D) thin finite-width shield made of imperfect material in the presence of the magnetic field from line source conductors. First, solutions to two canonical problems with closed-form simple analytic formulas are presented; shielding by reflection from and absorption in thin planar shields of infinite extent and shielding by perfect conductor shields of finite width. Then the method for calculation of magnetic-field shielding by perfect conductor finite-width shields is extended using the simple interpolation method, to thick shields made of imperfect material. Finally, the hybrid solution is developed by adding the two results in quadrature. The result is a simple theory for shielding by finite-width shields made of any real shielding material of arbitrary thickness. Its accuracy has been validated by comparison to finite-element method solutions and existing measurements.     

Shielding effect of hollow chiral sphere

The low-frequency shielding effect of a spherical layer is studied. The layer is made of a chiral material and it is electromagnetically characterized with three material parameters: permittivity, permeability, and chirality. Due to chirality, there is magnetoelectric coupling. The electric and magnetic shielding effects are derived and are shown to be functions of the three material parameters and also the relative thickness of the layer. Illustrations display the effects of the various parameters on the shielding, which is different for the magnetic and electric fields. Among the special effects is that the shielding increases rapidly as the chirality parameter approaches the refractive index of the shell. This makes chiral shells in principle effective shields, and in the future they may offer an alternative to conducting materials for novel shielding applications     

电磁屏蔽和吸波材料的研究进展

阐述了研究电磁屏蔽材料和吸波材料的重要性,分析了在不同情况下电磁屏蔽材料和吸波材料的作用机理。综述了常见的电磁屏蔽材料的种类以及各种屏蔽用涂料、填料的特点,同时介绍了吸波材料的种类和研究热点,并着重讨论了导电填料、基体、复合工艺等因素对其屏蔽效能的影响关系。最后对电磁屏蔽材料和吸波材料的研究和发展趋势也作了简要的阐述。     

密闭机柜磁场屏蔽效能研究

本文介绍机柜的电磁屏蔽原理和影响屏蔽效能的因素,对某舰载密闭铸铝机柜的低频磁场屏蔽效能进行了测试,得出具有工程实用价值的数据,对同类机箱机柜的屏蔽效能有参考评估作用,并针对本机柜门、结构和材料对屏蔽效能的影响给出了详细分析。     

Shielding effectiveness of rectangular cavity made of a new shielding material and resonance suppression

New shielding material has become an alternative to traditional metal to shield boxes from electromagnetic interferences. This article introduces the theory of transmission line method to study the shield boxes made of a new sort of material, and then expands the fundamental formulas to deal with the cases of multiple holes and polarization with arbitrary angle. By means of genetic algorithms with the aid of a three dimensional simulation tool, the damping of electromagnetic resonances in enclosures is researched. The computation indicates that under resonant frequency, electromagnetic resonance results in low, even negative shielding coefficient; whereas, for the same areas, shielding effectiveness of a single hole is worse than that of multiple holes. Shielding coefficient varies when polarization angle increases, and the coupled field through the rectangular aperture with the long side parallel to the thin wire is much weaker than that with the long side vertical to the thin wire. By using the metallic-loss dielectric layer of optimized calculation on the internal surface of the cavity, the best result of resonance suppression has been realized with the same thickness of coating. Finally, according to the calculation result, suggestions for shielding are proposed.     

双面金属涂敷材料对高空电磁脉冲的屏蔽

计算了绝缘材料双面金属涂敷结构对高空电磁脉冲(HEMP)的屏蔽效果。针对HEMP 特点,理论和 数值分析表明:对常用材料,同样的总金属厚度,从一定频率起,绝缘材料双面金属涂敷的屏蔽效果优于单层同种金 属涂敷。该起点频率受到绝缘材料厚度以及金属电导率的影响,绝缘材料厚度越大、金属电导率越大,起点频率越 低,屏蔽效果越好。绝缘材料的介电常数对屏蔽性能的影响可忽略。