Multiresolution analysis of electrostatic discharge current from electromagnetic interference aspects

This paper reports an analysis of the electromagnetic interference (EMI) aspects of electrostatic discharge (ESD) resulting from high-speed moving discharge phenomena. An orthogonal wavelet transform, which enables multiresolution decomposition of time-domain waves, was used to analyze measured ESD currents. The results showed that the high-speed moving discharges can increase the maximum amplitude and power of ESD currents, and that high-frequency components in particular tend to be affected by the movements of discharge electrodes. In the case of high-frequency components of ESD currents generated by charging voltages of 2, 5, and 15 kV, it was observed that the maximum amplitude was increased by 1.40 to 3.43 times, and the energy, defined by the sum of signals squared, was increased by 2.15 to 12.1 times compared to the results for the low-speed discharges. Chaos attractors reconstructed from measured ESD currents also showed that high-speed moving discharges decrease the stability of ESD current waveforms. From these results, it is apparent that EMI power generated by ESD tends to increase in the case of high-speed moving discharges.     

Electromagnetic interference mitigation by using a spread-spectrumapproach

We investigate a new technique, referred to as spread-spectrum clock generation (SSCG), for reducing the level of radiated emission from devices with digital clock signals. To calculate the radiated emissions from such devices, we model the radiating geometry and compute the radiated field at a multitude of frequencies by using NEC-4, which is an electromagnetic field solver based on the method of moments (MoM). We consider a variety of modulating profiles for the spread spectrum clock and demonstrate that by using a frequency deviation of only 1%, we can achieve from 10 to 30 dB reduction in the radiated emission levels     

卫星地球站电磁干扰（EMI）测试

本文通过实际对电磁环境较为复杂的卫星地球站干扰测试和对测试数据进行了分析处理,阐述了卫星地球站EMI的测试问题.并且对测试过程中本机漏泄电平出现的假像干扰情况予于排除.     

变电站二次系统电磁干扰与预防

高强度的电磁场环境会在一定程度上影响到微机机电保护装置,比如变电站等大型电磁场环境会导致整个系统的运作失控.本文首先针对变电站二次系统电磁干扰的有关状况展开简单的研究,找出干扰要素,并制定出有效的预防对策.     

Electromagnetic interference on medical equipment by low-powermobile telecommunication systems

There have been a number of reports of electromagnetic interference (EMI) on electronic medical equipment caused by mobile telecommunication systems. In Japan, the use of the personal handy-phone system (PHS) has greatly expanded within urban areas, PHS handsets transmit EM signals at a frequency of 1.9 GHz and have a peak radiated power of 80 mW. This power level is lower than that of other mobile telecommunication systems. Two studies were carried out. One was to determine whether or not PHS interferes with electronic medical equipment in hospitals. We observed no EMI on electronic medical equipment when the PHS handset was in either the speaking mode or on standby. The second study was to observe EMI from 1.9-GHz signals at several radiation power levels. Although EMI was not observed at the radiated peak power of the PHS handset, EMI on some of the tested equipment was observed when the radiated power was ten or more times higher than that of the PHS handset     

Electromagnetic interference (EMI) of system-on-package (SOP)

Electromagnetic interference (EMI) issues are expected to be crucial for next-generation system-on-package (SOP) integrated high-performance digital LSIs and for radio frequency (RF) and analog circuits. Ordinarily in SOPs, high-performance digital LSIs are sources of EMI, while RF and analog circuits are affected by EMI (victims). This paper describes the following aspects of EMI in SOPs: 1) die/package-level EMI; 2) substrate-level EMI; 3) electromagnetic modeling and simulation; and 4) near electromagnetic field measurement. First, LSI designs are discussed with regard to radiated emission. The signal-return path loop and switching current in the power/ground line are inherent sources of EMI. The EMI of substrate, which work as coupling paths or unwanted antennas, is described. Maintaining the return current path is an important aspect of substrate design for suppressing EMI and for maintaining signal integrity (SI). In addition, isolating and suppressing the resonance of the DC power bus in a substrate is another important design aspect for EMI and for power integrity (PI). Various electromagnetic simulation methodologies are introduced as indispensable design tools for achieving high-performance SOPs without EMI problems. Measurement techniques for near electric and magnetic fields are explained, as they are necessary to confirm the appropriateness of designs and to investigate the causes of EMI problems. This paper is expected to be useful in the design and development of SOPs that take EMI into consideration.     

Electromagnetic interference to television reception caused by horizontal axis windmills

Electromagnetic interference to television (TV) reception produced by horizontal axis wind turbine generators or windmills has been identified and quantified by comprehensive theoretical and experimental studies. It is found that the rotating blades of a windmill can produce pulse amplitude modulation (PAM) of the total signal received, and that for an antenna so located as to pick up the specular or forward scattering off the blades, this extraneous modulation can distort the video portion of a TV signal reproduction in the vicinity of the windmill. The distortion is worst at the higher frequencies, and therefore, poses mote of a problem at UHF than VHF. Based on laboratory studies as well as on-site measurements, a modulation level has been established at which the video interference is judged "acceptable,' and this threshold of interference is substantially independent of the ambient signal strength. A theory has been developed to compute the interference region about a windmill for any given TV transmitter, and the results are in good agreement with those obtained from on-site measurements with an operational windmill.     

气体放电对 PDP 残像形成的影响及其改善研究

针对等离子体显示器维持期气体放电过程引起的PDP残像,研究了持续气体放电过程对残像可恢复性的影响以及相同放电条件下显示单元三基色亮度变化情况,分析了气体放电过程与PDP残像形成之间的关系,提出了通过调整PDP显示过程中工作气体的放电强度,补偿气体放电过程引起亮度差异的方法来减轻显示残像,改善残像对显示画质影响的方法。实验结果表明,该方法能够减少残像产生后的恢复时间,改善显示残像,提高显示图像画质。     

Electromagnetic interference (EMI) reduction from printed circuit boards (PCB) using electromagnetic bandgap structures

As digital circuits become faster and more powerful, direct radiation from the power bus of their printed circuit boards (PCB) becomes a major concern for electromagnetic compatibility engineers. In such multilayer PCBs, the power and ground planes act as radiating microstrip patch antennas, where radiation is caused by fringing electric fields at board edges. In this paper, we introduce an effective method for suppressing PCB radiation from their power bus over an ultrawide range of frequencies by using metallo-dielectric electromagnetic band-gap structures. More specifically, this study focuses on the suppression of radiation from parallel-plate bus structures in high-speed PCBs caused by switching noise, such as simultaneous switching noise, also known as Delta-I noise or ground bounce. This noise consists of unwanted voltage fluctuations on the power bus of a PCB due to resonance of the parallel-plate waveguiding system created by the power bus planes. The techniques introduced here are not limited to the suppression of switching noise and can be extended to any wave propagation between the plates of the power bus. Laboratory PCB prototypes were fabricated and tested revealing appreciable suppression of radiated noise over specific frequency bands of interest, thus, testifying to the effectiveness of this concept.     

放电准分子激光电磁干扰环境下控制系统设计

为了在放电激励准分子激光的电磁干扰环境下,实现有效的抗干扰控制系统设计,采用全光纤接口设计和基于电压频率转换实现的高精度模拟信号传输的方法,取得了放电准分子激光空间电磁干扰强度和压频转换波形等数据,进行了理论分析和实验验证。结果表明,在最强电场干扰14V/m、最强磁场干扰38A/m的条件下,系统能够实现误差小于2.5%的模拟信号稳定传输,工作稳定可靠。这一结果对分析和设计能够稳定工作并抗干扰的准分子激光器控制系统是有帮助的。     

Electromagnetic scattering interference between two shallow objects buried under 2-D random rough surfaces

A rigorous electromagnetic model has been used to analyze the scattering from two dielectric shallow objects buried under the two-dimensional (2-D) random rough ground (3-D scattering problem) as a means of predicting false alarms. The method of moments (MoM) accelerated by the steepest descent fast multipole method (SDFMM) is used to compute the equivalent electric and magnetic surface currents on all scatterers (i.e., the rough ground and the two buried objects). The roughness parameters influence the scattering interference mechanism of the two objects, however, a large separation distance (e.g., several correlation lengths) showed stronger effect for small ground roughness.     

低压大电流整流电源电磁干扰分析及主动屏蔽技术

本文通过对一套低压大电流整流柜的周围的电磁场进行理论分析,得出了整流柜电磁场分布的规律,并通过实验测试对理论分析结果进行了验证,提出了抑制整流柜电磁干扰的措施,为整流电源系统实主动屏蔽提供了技术支撑。     

Electromagnetic radiation from heterogeneous plasma

It was found that the electromagnetic radiation frequency, strength, and waveforms from a heterogeneous plasma were independent of the circuit but were influenced by the material of the electrodes. Using the same circuit for various electrodes, radiation ranging from 10 to 50 MHz, power from 0.5 to 200 mW, and sinusoidal to spiked waves were observed.     

Electromagnetic scattering from dielectric bodies

Far-field results obtained by two different methods are compared for the problem of electromagnetic scattering from dielectric objects. The two methods are the surface integral formulation, utilizing equivalent electric and magnetic surface currents, and the volume formulation, utilizing the equivalent electric polarization current. Triangular patches are used in the surface formulation and cubical cells are used in the volume formulation. The far-scattered fields obtained by the two methods are in good agreement, thereby validating both the approaches for the analysis of scattering problems. Numerical problems associated with the fields in the source region are also addressed     

Electromagnetic Interference from Pocket Calculators

Presented are the results of an investigation of the near-field Electromagnetic Interference (EMI) associated with the operation of pocket calculators. A review of the regulations governing the permissible levels of interference from portable electronic equipment is undertaken, and subsequently, the results of EMI measurements on three pocket calculators are presented. The results indicate that near-field EMI levels are of sufficient magnitude to make questionable the unrestricted operation of a pocket calculator in an electromagnetically sensitive environment, such as found on an aircraft flight deck. Finally, a simple and inexpensive means of eliminating this interference is investigated.     

Magnetism from conductors and enhanced nonlinear phenomena

We show that microstructures built from nonmagnetic conducting sheets exhibit an effective magnetic permeability μ_eff, which can be tuned to values not accessible in naturally occurring materials, including large imaginary components of μ_eff. The microstructure is on a scale much less than the wavelength of radiation, is not resolved by incident microwaves, and uses a very low density of metal so that structures can be extremely lightweight. Most of the structures are resonant due to internal capacitance and inductance, and resonant enhancement combined with compression of electrical energy into a very small volume greatly enhances the energy density at critical locations in the structure, easily by factors of a million and possibly by much more. Weakly nonlinear materials placed at these critical locations will show greatly enhanced effects raising the possibility of manufacturing active structures whose properties can be switched at will between many states     

两例CDMA基站干扰的查找与启示

无线电干扰是指在射频频段内,可能对有用信号造成损害的无用信号或电磁骚扰。按干扰源的性质,分为自然干扰和人为干扰两大类。自然干扰来源于自然现象,是不可控制的,主要有天电干扰、太阳干     

Reduced reflections from multimode interference couplers

A 3 dB multimode interference (MMI) coupler optimised for low reflections is presented. The MMI was designed, fabricated and characterised. For comparison, MMIs with non-optimised layout have been included on the same sample. The measurement results show a reduction in reflectivities of more than 10 dB.     

丰垒场馆赛前排查模拟信号电视干扰纪实

7月26日下午,安徽团队丰台体育中心垒球场无线电工程师在进行监测工作时发现,场馆技术副经理的集群手机只要触发PTT键,技术部房间里正在播出CCTV-5奥运频道节目的电视画面就会出现蓝屏。调至其他两套模拟电视频