Radiated emissions and immunity of microstrip transmission lines:theory and reverberation chamber measurements

The increasing complexity of electronic systems has introduced an increased potential for electromagnetic interference (EMI) between electronic systems. We analyze the radiation from a microstrip transmission line and calculate the total radiated power by numerical integration. Reverberation chamber methods for measuring radiated emissions and immunity are reviewed and applied to three microstrip configurations. Measurements from 200 to 2000 MHz are compared with theory, and excellent agreement is obtained for two configurations that minimize feed cable and finite ground plane effects. Emissions measurements are found to be more accurate than immunity measurements because the impedance mismatch of the receiving antenna cancels when the ratio of the microstrip and reference radiated power measurements is taken. The use of two different receiving antenna locations for emissions measurements illustrates good field uniformity within the chamber     

Currents induced on multiconductor transmission lines by radiationand injection

Multiconductor transmission line theory is used to compare current induced on individual wires within a bundle by injection and radiated excitation. Calculations show that the two types of excitation generally induce significantly different current distributions, but the differences are much smaller for electrically short lines. The results are relevant to the validity of using current injection testing to replace radiated immunity testing     

无线移动终端辐射杂散测试

辐射杂散测试是评估无线移动终端辐射性能的有效方法。文章阐述了进行无线移动终端辐射杂散测试的技术要求、限值和测试方法;着重总结和归纳了在测试过程中需要注意的技术细节;同时对LTE移动终端辐射测试的带来的新问题进行了预分析。     

Testing times for analogue products

The test requirements of the second edition of the European generic immunity standard for residential, commercial and light industry environments (EN50082-1: 1997), differ substantially from those of the first edition (EN50082-1: 1992). In the first edition, the frequency range for radiated immunity testing was 27 MHz to 500 MHz. The second edition extends the frequency range to cover 150 kHz to 80 MHz (for conducted immunity) and 80 MHz to 1000 MHz (for radiated immunity). It also specifies that all RF tests feature amplitude modulation with 1 kHz at a depth of 80% in accordance with EN 61000-4-3 (radiated) and EN 61000-4-6 (conducted). Many product types that formerly complied with the radiated immunity test requirements are failing to comply with the amplitude modulation tests specified in the new edition. As a consequence, wise design engineers will want to re-examine their existing product designs, while reflecting carefully on specific areas on their new product development projects. The author offers guidance and advice for the concerned design engineer     

车外源辐射抗扰性试验中功率放大器的选择

车外源辐射抗扰性试验已经成为国内汽车电磁兼容实验室必须具备的试验能力之一。通过理论分析和实际测量,对200～1000MHz频率范围内达到不同严酷电平需要的功率进行了估算,提供了该试验功率放大器的配置方法。     

汽车零部件的雷达波抗扰度测试

介绍雷达波辐射场抗扰度测试方法,指出雷达波测试是汽车零部件抗干扰能力的有效验证方法。阐述在测试布置、校准和信号调制三个方面与一般辐射场抗扰度测试的不同,认为场强高、校准难度大、脉宽窄是产生差异的主要原因。     

射频电磁场抗扰度测试方法的研究

本文讨论了射频电磁场抗扰度的测试方法。此外,通过模拟单极子天线的空间发射原理证明了在其发射状态下具有很强的空间辐射场强,也为实际检测工作提供了理论依据。     

混响室条件下线缆差模干扰辐射敏感度测试研究

为在混响室中对线缆差模干扰时的设备进行辐射敏感度测试,基于BLT方程,以常见的平行双导线为研究对象,分析了差模干扰时影响线缆方向性系数的因素,计算了线缆最大方向性系数的取值范围。然后根据前期研究中提出的测试方法,在混响室中和开阔场中进行试验,对计算结果进行了验证。试验结果表明,按照所得的最大方向性系数的计算值,可以确保混响室中辐射敏感度测试结果与开阔场相一致。     

Understanding electrosurgical unit perturbations in order to address hospital operating room electromagnetic compatibility

We analyze the radiated emissions from a low power electrosurgical unit (ESU). Measurements at a 3-meter distance are performed in order to find a suitable measurement setup intended to reproduce realistically the real working ESU behavior in a test lab. The broad-band and narrow-band characteristics of the perturbation are studied in order to address the other equipment immunity.     

基于优势效应理论的双绞线简化建模

一些学者对双绞线电磁干扰进行研究,建立了精确的干扰模型,但并不适合工程应用.为此根据电磁兼容优势效应理论,推导出双绞线传导干扰主要由差模电流引起,辐射干扰主要由共模电流引起.分别利用广义二端口网络模型和电流元分析方法建立双绞线串扰和辐射的简化模型,从而有效估算双绞线串扰电压和对外辐射场的大小,最后给出滤波连接器的选择方法,为工程人员采取有效措施抑制互连设备电磁干扰提供了理论帮助.     

A reflection coefficient derivation for the Q of a reverberationchamber

Reverberation chambers (also called mode-stirred chambers) are multimoded cavities that are used for radiated emissions or immunity measurements. A reflection coefficient method is used to derive the quality factor (Q) of reverberation chambers of arbitrary shape. The results are applicable to walls of general materials, but reduce to the previous result for highly conducting walls with small skin depth. The reflection coefficient method is also used to derive the decay time of reverberation chambers     

A comparison of the contributions of common-mode anddifferential-mode currents in radiated emissions

It is shown that radiated emissions due to common-mode currents on printed circuit board lands can greatly exceed those due to differential-mode currents. It is concluded that predictions of radiated emissions based solely on differential-mode (transmission line) currents can bear little, if any, resemblance to actual measured emissions. Therefore, radiated emission prediction models that use only differential-mode (transmission-line) currents and ignore common-mode (antenna) currents are not adequate for the prediction of radiated emissions from printed circuit boards (as well as cables)     

PCB板级双绞互连结构减小感性和容性串扰噪声

非屏蔽双绞线已经被广泛的运用于网络的互联中,双绞的结构能够提高对串扰和辐射发射的抵抗能力。在高速数字电路的PCB板上差分信号变得越来越多。随着上升时间的加快,差分信号的信号完整性问题变得越来越重要。最近,一种新的双绞差分传输线被引入到布线中。文章通过理论和仿真分析了这种双绞差分线结构如何减小串扰和辐射发射。     

Analysis of Radiated Emissions From a Printed Circuit Board Using Expert System Algorithms

Three algorithms developed for expert system electromagnetic compatibility tools are used to evaluate a printed circuit board design. The maximum radiated emissions estimated by the algorithms are compared to the measured data for various board configurations. The algorithms identify the most important electromagnetic interference source mechanisms, drawing attention to the design parameters that have the most significant effect on the radiated emissions     

电子称重仪表辐射抗扰度测试的方法与对策

介绍了电子称重仪表射频辐射抗扰度(RS)测试的测试标准与方法。结合某型电子称重仪表RS测试,归纳总结出提高电子称重仪表辐射抗扰能力的一些基本方法和设计要点,对提高仪表可靠性,顺利通过RS测试有一定的参考意义。     

基于VB的电能表射频电磁场辐射抗扰度试验自动测试系统设计和开发

针对电能表射频电磁场辐射抗扰度试验的特殊的情况,设计并开发了电能表射频电磁场辐射抗扰度试验自动测试系统,该系统包括信号发生器、功率放大器和电能表检验装置等设备,通过串口设备进行通讯,基于VB开发系统软件,使用情况表明该系统行之有效,具有良好的实时性和准确性,可以完全满足电能表射频电磁场辐射抗扰度试验的要求。     

开关电源散热器的辐射发射

开关电源电路中,接地散热器提供了一条共模骚扰高频谐波电流的通路,使共模传导电磁干扰增加;非接地散热器切断了共模传导电磁干扰的通路,但增强了散热器辐射发射,射频辐射的增强能够引起设备误操作或者违反目前的电磁兼容性标准.文中分析功率开关管散热器产生辐射发射和共模传导电磁干扰的机理.采用有限元方法,通过电磁场数值计算,探讨非接地散热器的几何形状、尺寸和安装方式对其辐射发射的影响.数值计算结果表明:散热器面积越大、高次谐波频率越高,辐射电场幅值就越大,但是辐射电场幅值与散热器面积、高次谐波频率无线性关系;相同面积的散热器中,圆形散热器的散热效果最佳、辐射电场最小.因此,开关电源设计中,应根据散热效果、辐射EMI和共模传导EMI,综合考虑散热器面积、形状的选择,以及散热器是否接地.     

视频电话终端机射频辐射抗扰度研究——北美NEBS认证

视频电话终端机的使用越来越广泛,但是其抗辐射干扰性能却非常薄弱。本文基于这种情况,分析了辐射抗扰度的测试原理和出现的问题,并从信号线的选取、布置和电路设计两方面出发,提出了一系列的对策措施,增强电话会议终端机的射频辐射抗干扰能力。     

混响室校准与辐射抗扰度测试

在对混响室的基本原理进行简要介绍的基础上,依据标准IEC61000-4-21中的规定,对混响室的校准方法及操作过程进行了详细介绍和分析,并对在混响室内进行辐射抗扰度测试的方法及步骤进行了介绍。     

静止式电能表射频电磁场辐射抗扰度试验整改

在对一款典型性单相静止式电能表电流采样信号输入端进行增加瓷片电容、串联磁珠和电流采样信号短路等试验和分析的基础上,总结提出一些针对射频电磁场辐射抗扰度试验的解决方案,整改后的电能表通过了射频电磁场辐射抗扰度试验。