Near-field diagnostics of small printed antennas using theequivalent magnetic current approach

A near-field to far-field transformation based on the antenna representation by equivalent magnetic current (EMC) sources has been proposed and validated experimentally on large high-directivity antenna arrays. In this paper, the use of EMC is extended to the diagnostics of low-directivity printed antennas. The limitation of the near-field to far-field transformation applied to EMC models of low-directivity antennas, caused by the finite dimensions of the antenna ground plane, is demonstrated. A method to partially overcome this limitation by including the contribution of diffracted rays is implemented, and its effectiveness is demonstrated with antenna prototypes. It is shown that the agreement between the far-field patterns measured in an anechoic chamber and the patterns computed from the EMC model obtained from the near-field measurements is significantly improved upon, within a sector of ±90° with respect to the antenna boresight in the E plane. The influence of the near-field sampling density and topology of the EMC model on the accuracy of the predicted far-field pattern is examined     

近场EMC测试技术

随着电探头、磁探头和电磁算法的不断完善,近场扫描技术有望与电磁兼容暗室、微波混响室等一起构成近场、远场一体化的电磁兼容测试系统。总结了近场测试技术的一些进展,主要包括利用感应区的电磁场重构等效辐射源,测量弱辐射体的屏蔽效能,以及多分量电磁探头的设计。     

基于有限元法的高频开关电源PCB电磁兼容设计与仿真

在高频开关电源的设计中,功率开关器件在高频下的通断会产生强大的EMI,所以不可避免的会出现电磁兼容问题。这篇文章应用有限元法分别对自动布线后的高频开关电源PCB与按照电磁兼容设计规则布线后的PCB进行仿真,得到其在200 MHz、600 MHz、1 GHz频率处的近场辐射参数。仿真结果表明:自动布线生成的高频开关电源PCB近场辐射的范围和数值均较大,电磁干扰较强。根据电磁兼容的相关规则对PCB进行优化后,近场辐射的范围和数值均有所减小,提高了PCB板的电磁兼容性。     

EGSM/TD-LTE双模双连接手机近场电磁兼容的研究

针对EGSM/TD-LTE双模双连接手机,研究了手机近场的电磁兼容问题。首先构建了EGSM和TD-LTE两个模式的手机近场电磁兼容问题的评估模型;其次基于该评估模型研究了近场射频干扰与双模双连接手机接收性能的关系,当EGSM的发射功率为30dBm,TD-LTE系统的接收灵敏度会恶化2dB;最后给出了一种提高多频段双天线隔离度的解决方案,并通过仿真表明,该方法能够有效提高双模双连接手机的天线隔离度,从而克服双模双连接手机的电磁兼容问题。     

Cube probe structures for integrated near-field scanner module

Two new miniature near-field 'cube probe' structures for EMC/EMI measurements are proposed. Their performances are compared to those of the classical H-field loop probe in two orthogonal planes. The single cube probe effectively replaces three conventional orthogonally oriented loops. An array of cube probes is also proposed to form a near-field scan module dedicated to the characterisation of integrated circuit radiated emissions.     

Spherical near-field facility for microwave coupling assessments inthe 100 MHz-6 GHz frequency range

This paper describes a spherical near-field facility set up at the Centre d'Etudes de Gramat (CEG) to perform low-power microwave coupling assessments. Specifically, this facility has been designed to determine the coupling cross section of a complex object. However, it can also be used for the characterization of any radiating system in electromagnetic compatibility (EMC) or high-power microwave (HPM) environments. The near-field approach is shown to be complementary and to offer increased flexibility when compared to other more conventional measurement techniques. More particularly, the use of a probe array in the upper part of the frequency band significantly speeds up the near-field measurement process. Consequently, broadband and multiparameter acquisitions can be performed within acceptable duration. The examples given in this paper provide a broad illustration of the capabilities of near-field techniques for EMC and HPM applications     

Far-field predictions from near-field measurements using an exactintegral equation solution

This paper presents a new approach to derive far-field data needed in antenna and EMI/EMC testing from near-field measurements. An exact integral equation solution to the wave propagation problem is used to transform the near-field data to the far field. The method requires near-field measurements on two closed surfaces enclosing all sources and inhomogeneities. The approach is validated with numerical simulation of measurements of fields radiated from a known antenna     

Applications of the Near-Field Techniques in EMC Investigations

A completely automatic near-field mapping system has been developed within the Research Institute for Electronic Embedded Systems (IRSEEM) in order to determine the electromagnetic field created by electronic systems and components. This test bench uses a 3-D positioning system of the probe to make accurate measurements. This paper presents some applications of the near-field techniques in EMC investigations. In the first part, near-field measurements are used to locate precisely the electromagnetic sources of a limiter device. In the second part, we present an equivalent model of the radiated emission of an integrated circuit. In the last part, the near-field test bench is used to characterize faults in a cable.     

电磁兼容自适应扫描系统的研制

针对近场测试系统的市场需求及该系统在国内相关领域的研究空白,设计并实现了一款新型电磁兼容扫描系统。该系统可对PCB板、线缆、机箱等被测设备进行全局扫描、局部扫描或自适应扫描,并以三维彩色图形的形式显示被测设备的电磁辐射状态,实现电磁场＂可视化＂。提出了＂自适应扫描＂原理,设计并实现了步进长度可调整的自适应式扫描的技术方案,从而达到节省扫描时间、提高效率并降低成本的效果。     

屏蔽材料在汽车电子EMC中的应用

介绍了用屏蔽材料解决汽车电子EMC问题的几种典型解决方案,包括车载电子设备的屏蔽应用、汽车电子设备连接线束的电磁屏蔽、汽车电子设备近场骚扰和接地应用措施等,实际应用表明：具有优异抗环境特性的导电胶带、屏蔽套管、软磁胶带等产品,可有效解决汽车电子的EMC问题。     

Ferrite Polymer Composite for Improving the Electromagnetic Compatibility of Semiconductor Packaging

The complex permittivity and permeability of ferrite-filled polymer composites were studied at 50 MHz to 1 GHz, and their effects on the electromagnetic compatibility (EMC) of an integrated circuit (IC) package mounted on a printed wiring board (PWB) in the far- and near-field modes were investigated. Incorporating the ferrite particles into the polymer increased the real part of the complex permeability to 10–11 at 50 MHz, and the real part exhibited a frequency dependency over the applied frequency range (50 MHz to 1 GHz). The ferrite particle increased the magnetic loss (μ″ = 3–5) as well, which can absorb the magnetic energy of the incident electromagnetic wave. By coating the test IC package with the ferrite-polymer composite materials, the EMC level of the PWB was dramatically improved. This improvement may be due to the high magnetic loss of the ferrite-polymer composite.     

EMC重在设计

EMC是业界的一个难点;文章介绍了EMC三个规律、EMC问题三要素、电磁骚扰的特性、以及五层次EMC设计法;给企业提供了对待EMC的建议;作者认为EMC改进要如诊治疾病一样对症施治;作者倡导坚持EMC规律,趁早考虑和解决EMC问题-进行EMC设计.     

基于复杂系统的电磁兼容设计方法可行性分析

目前,电磁兼容(EMC)设计已成为复杂系统设计的一个重要组成部分,电磁兼容设计方法主要有测试分析法、经验分析法和建模仿真法三种。从日益复杂的电磁环境的要求出发,结合高度集成的复杂系统电磁兼容设计的实际困难以及电磁兼容设计人员的具体情况,分析测试分析法、经验分析法和建模仿真法这三种电磁兼容设计方法的可行性,指出三种方法的适用范围和面临的问题,从实用角度提出建立电磁兼容数据库,将电磁兼容测试数据、电磁兼容设计经验和电磁兼容模型全部入库的建议,对提高复杂系统的电磁兼容性具有现实意义。     

A practical strategy for EMC design

The introduction of the European EMC Directive has made it very important that engineers design for EMC in their products from the start. The paper describes a strategy to ensure that EMC aspects of design are considered in a logical sequence during development. This strategy is discussed, checklists for EMC design are introduced and a number of important design areas highlighted     

论军用装备研制中的电磁兼容性控制

电磁兼容性作为武器装备的一种性能,受到越来越多的重视。该文就军用装备电磁兼容性控制的三个主要方面:电磁兼容性管理、电磁兼容性设计和电磁兼容性试验展开讨论,并结合产品科研生产的全寿命周期内的电磁兼容性活动,详细分析了各部分的功能,涉及的主要内容,以及相应的操作方法等。     

汽车电磁兼容仿真预测技术探讨

汽车电磁兼容仿真预测技术是近年来新出现的研究热点。本文介绍了汽车电磁兼容仿真预测与电磁兼容标准、测试的关系及其在汽车电磁兼容设计中的地位,对汽车电磁兼容仿真的主要研究内容进行了阐述,并给出了建立仿真模型的具体方法,以促进我国汽车电磁兼容仿真预测技术的发展。     

机载计算机电磁兼容性设计

介绍了电磁兼容的定义、目的,设计步骤、试验项目和要求,针对机载计算机电磁兼容的特点和工程实践,提出解决机载计算机电磁兼容问题重点关注的四个方面,即电缆设计、机械结构设计、电源滤波器设计和计算机电源接地和信号接地设计。通过总结机载计算机设计和电磁兼容试验中出现的具体问题,从理论上分析问题产生的机理,提出切实可行的工程解决方法。最后强调该技术是试验性的科学,解决方案必须通过电磁兼容试验验证。     

高速混合电路的EMC设计

高速混合电路在很多重要领域都有应用.高速混合电路中的主要噪声源和EMC设计方法都有新的重要特点,传统的EMC设计方法已难以满足实际需要.结合IC技术、PCB技术和EMC技术的新进展和发展趋势,讨论了高速混合电路中的主要噪声源(包括△I噪声、时钟噪声、电源噪声、ESD噪声等),研究了高速混合电路的若干值得重视与进一步研究的EMC设计方法(涉及IC封装技术、PCB技术、EMC预测技术、EDA技术、时钟展频技术、ESD防护技术等).对高速混合电路的EMC设计方法的研究与应用具有指导作用.     

电磁兼容性通用测量模型研究

以电磁兼容性测量标准为研究对象,建立了具体项电磁兼容性测量模型,据此总结出了硬件类模型和属性模型.在这两个模型基础上,建立了基于类的电磁兼容通用测量模型,该模型是最终建立电磁兼容性测量系统计算机辅助优化设计的基础.