2014 IEEE EMC国际学术研讨会——提名文章(一)

探讨了30 MHz~1 GHz电场辐射发射3米法测试中,受试设备(EUT)的尺寸问题。对比了不同标准中对辐射发射测试的布置要求,给出了EUT和对数周期天线主瓣宽度的适应尺寸。     

互连电缆电磁辐射的抑制方法研究

在电子设备的电磁兼容(EMC)测试中,被测设备(EUT)的互连电缆电磁辐射较难抑制.本文通过交调干扰分析得出EUT内部的可能产生的频谱,并对这些频谱进行滤波处理,使其耦合到电缆线上的电磁辐射较小,同时对电缆上的电磁辐射进行屏蔽处理,保证EUT能通过EMC的辐射发射测试.     

EMC测试中线缆辐射分析及抑制

在EMC测试中,被测设备(EUT)的电缆电磁辐射较难抑制.本文通过交调干扰分析得出EUT内部的可能产生的频谱,并对这些频谱进行滤波处理,使其耦合到电缆线上的电磁辐射较小,同时对电缆上的电磁辐射进行屏蔽处理,保证EUT能通过EMC的辐射发射测试.     

电磁兼容辐射发射测试中的误差分析

电磁兼容辐射发射测试是对受试设备（EUT）往空间辐射电磁波能量大小的进行测量的主要手段,由于各种原因不可避免地存在测量误差。因此,文章在概述误差理论的基础上,着重分析了标准辐射发射测试和预辐射发射测试的误差来源,同时依据标准电场强度的数学模型,简化得到预辐射发射电场强度的数学模型。     

虚拟暗室背景滤除模式性能分析

通过信号源模拟EUT 信号小于背景环境、EUT 信号等于背景环境、EUT 信号大于背景环境及EUT 信号与背景 环境不同频率时的试验研究虚拟暗室背景滤除模式，进一步得出虚拟暗室背景滤除模式的工作条件和方式。     

CISPR／B

1 CISPR／BWG1的工作项目 CISPR 11的维护 关于加入一个3米的测量距离时电缆布置以及在场强测量过程中周边设备的处理方法，会议决定将CISPR／B／489／INF中提出的文本修改为：对于3米的测量距离，对EUT电缆辐射的评估应当限制在那些互相连接的电缆部分（见7．5．2），供电电缆（见7．5．3）的部分应包括在直径1．2m、离地高度1．5m的试验空间。那些不满足试验空间要求的外同设备应被排除在测量之外（或者拆除），     

GB/T 17618-2015解析

分析了GB/T 17618-2015在静电放电、电快速瞬变脉冲群、射频连续波骚扰及浪涌抗扰度测试技术内容的变化,其中:ESD测试步骤有所简化、EFT测试中对设备电缆长度的要求有所放松、射频连续波骚扰测试中对大体积EUT辐照方式有新要求。对新标准的适用性、EUT状态、测量不确定度及附录进行了说明。     

EUT对TEM传输室基本特性影响的边界元分析

采用边界元法分析了不同尺寸的良导体受试设备(Equipment Under Test，EUT)对TEM传输室特性阻抗和场分布的影响，并估算了敏感度测试中EUT所承受暴露场强的大小。计算结果表明：与空载时相比当EUT满足“1／3准则”时，TEM传输室的特性阻抗下降值小于2Ω，EUT上、下方场强增加3～4dB，EUT上部所承受暴露场强比通常的估算方法高约4～6dB。测量结果与计算结果基本一致。     

FCC认证中5 GHz Wi-Fi设备的DFS测试

主要介绍FCC认证中5 GHz Wi-Fi设备的动态频率选择(DFS)测试要求,以不带雷达监控功能设备为例来讨论DFS的测试要求。通过介绍雷达波形、信道移动时间和信道停止传输时间、信道非占用时间等项目来判定EUT是否通过DFS的测试要求,并对测试项目具体操作规范及判定依据作出具体说明。     

骚扰功率与辐射骚扰场强

介绍了GB 13837标准中规定的两种考察受试设备(EUT)对外辐射能量的测试方法,即骚扰功率测试和辐射骚扰场强测试.分别阐述了两种方法的区别,并结合实践提出问题.通过试验证明骚扰功率和辐射骚扰场强的测试结果无法相互转换.从而得出结论,针对音视频功能,不论其工作频率如何,都应进行骚扰功率测试.     

TEM传输室置入金属EUT后场分布的边界元分析

横电磁波传输室广泛应用于电磁兼容试验中，当置入受试设备后，其中的场分布会发生扰动。本文采用边界元法分析了横电磁波传输室中置入金属箱体的受试设备后场分布的规律，对受试设备所受暴露场的场强进行了计算，并提出了具体的估算方法。对空载时横电磁波传输室的场分布进行了测量，测量结果证实了计算方法的正确性。     

A Comparison of the Currents Induced on an EUT in a TEM Cell to Those Induced in a Free-Space Environment

The finite-difference time-domain method is used to investigate whether the currents induced on equipment under test (EUT) in a transverse electromagnetic (TEM) cell are similar to those induced in a free-space environment. The approach is to simulate an identical EUT in both environments and determine a correlation based on the respective current distributions. The effect of the ratio of EUT to TEM cell sizes on the correlation to free space is also investigated. This paper introduces a metric that quantifies the change in the surface current induced on the EUT in these different environments.     

通信电台电磁脉冲阻塞效应规律与作用机理

为揭示通信电台电磁脉冲阻塞效应机理,在受试电台正常工作状态下,借助注入耦合模块实验研究了阶跃脉冲串和双指数脉冲串对数字通信电台误码率的影响规律。引入电磁脉冲对受试设备影响时间的概念,建立了与连续波阻塞效应等价的电磁脉冲阻塞敏感判据。实验结果表明:电磁脉冲对受试设备的影响时间取决于脉冲波形,可通过效应试验测试确定。在电磁脉冲重复率较低时,受试电台的临界干扰电平与脉冲重复率无关,属于单脉冲效应;当脉冲重复率大于电磁脉冲影响时间的倒数时,受试电台的临界干扰电平随脉冲重复率增加而降低,属于多脉冲累加效应。将电磁脉冲在影响时间窗口内进行频谱分析,采用连续波带内多频阻塞效应模型进行验证,误差在2dB以内。     

近场辐射电磁干扰模态测试系统设计

提出近场辐射电磁干扰模态测试方法,设计近场模态检验测试系统,采用近场电磁场头对待测设备进行扫描式测量,获得待测设备的近场电磁场分布情况,并根据测得电磁场强度大小可分析得到待测设备的辐射EMI模态。实验结果表明,该方法可对电子电路的近场辐射EMI模态进行有效识别和检验,分别得到近场辐射共模噪声和差模噪声EMI模态,为辐射电磁干扰噪声的抑制提供有益参考。     

基于频域块LMS算法的实时虚拟暗室测试方法

针对电磁辐射现场测试被测设备信号和干扰未知的情况,提出了一种基于频域块最小均方算法的实时虚拟暗室测试方法。该方法采用双通道接收机,根据测试通道和背景通道中干扰信号的相关性设计自适应滤波器,在频域对背景通道信号滤波以趋近测试通道中的干扰分量,采用瞬时双通道信号迭代更新滤波器系数,滤波器系数收敛后系统输出中只有被测设备信号。仿真与分析表明,该方法在背景通道有无被测设备信号泄露的情况下都能有效抑制干扰,与基于时域最小均方算法的方法相比,在滤波器长度相同的情况下其计算复杂度更低,适用于实时现场测试。     

加载横电磁传输室中的电场分布计算

用“准静脉法”研究了当工作频率远低于截止频率时,放置于横电磁传输室中的被测物体中的电场分布。文中使用的是有限差分法,给出了在三维空间中不同介质交界面上拉普拉斯方程的差分格式。计算结果表明当把ＥＴＵ放入ＴＥＭＣｅｌｌ的中心时,ＥＵＴ横截面上的电场分布是均匀的。     

A Method to Minimize Emission Measurement Uncertainty of Electrically Large EUTs in GTEM Cells and FARs Above 1 GHz

This paper presents an emission measurement technique with reduced uncertainties for electrically large equipment under test (EUTs) in gigahertz transverse electromagnetic (GTEM) cells and fully anechoic rooms (FARs) above 1 GHz. A small and a large EUT were measured and the results obtained in the GTEM cell were validated against those obtained in a FAR. Measurements in a FAR were made, for the small EUT, in the conventional way with an azimuth scan and, for the large EUT, with a limited antenna height scan. Key findings are that similar scanning is required in the GTEM cell and that the three-orthogonal-position (TOP) method of EN61000-4-20 is not appropriate for EUTs that have multilobed radiation patterns. In other words, GTEM cells and FARs are sensitive to directional properties of EUTs, and both methods require further scanning for electrically large EUTs     

A treatment of the phase properties of GTEM to open-area test-sitecorrelation techniques

The gigahertz transverse electromagnetic (GTEM) cell is a very attractive environment for the measurement of radiated emissions from electrically small equipment under test (EUTs). However, the GTEM is only accepted by the relevant measurement standards as long as the measurements in a GTEM can be used to predict the field that a particular EUT would produce on an open-area test site (OATS). Techniques for predicting equivalent OATS radiated fields from measurements in a GTEM have been developed. The techniques include the assumption that the dipole moments, which represent the radiation of an EUT, are all in phase. We analyze the case where the EUT dipole moments are not in phase and propose a new upper limit for the predicted OATS radiated field. Our new limit is up to 5 dB greater than the maximum predicted by the existing techniques, but over most of the frequency range the difference with the existing technique is about 3 dB     

On the Interplay Between the Equipment Under Test and TEM Cells

In all applications of the gigahertz transverse electromagnetic (GTEM) cell, there is an interplay between the equipment under test (EUT) and the cell reflecting metal walls, as represented by images of the EUT. Moreover, owing to the multiple reflections within the cell and to its tapering structure, the phenomenon of illumination and reillumination of the EUT can hardly be avoided. These problems, known as reactive effects of the cell, are investigated in this paper. A simple new approach for an efficient investigation of the interactions between the EUT and the cell is provided. Closed-form expressions for the reflection coefficient, the relative deviation in field, and the relative error in the induced current caused by the reactive effect of the cell are derived. Each of these expressions encompasses both the mutual influence of the EUT's radar cross section (RCS) and the reactive effects of the cell. It is shown that depending on the frequency-dependent phase factor e^jpsi, strong and weak test conditions may occur since the overall incident field will exhibit maxima and minima. Hence, evidence showing that the total incident field impinging on the EUT generally deviates from the primary excited TEM field is provided. Moreover, the relative deviation in the field and the relative error in the induced current are quantified. Finally, the frequency dependence of the well-known one-third-rule of thumb is demonstrated.