抑制同步开关噪声的新型超宽带电磁带隙结构

提出一种新型超宽带电磁带隙结构,以抑制印刷电路板(PCB)上的同步开关噪声.基于电磁带隙结构的理论分析和设计,对新型电磁带隙结构的阻带特性及信号完整性进行了仿真分析.仿真结果表明,与相同参数的Z型桥电磁带隙结构比较,新型电磁带隙结构的阻带带宽提高,下截止频率降低;同时使用差分线对传输信号时,新型电磁带隙结构电源平面保持了较好的信号完整性.     

超宽带抑制同步开关噪声的新型电磁带隙结构

为抑制现代高速电路中的同步开关噪声,给出了一种新型电磁带隙结构,可超宽带抑制同步开关噪声。利用软件对新型电磁带隙结构的阻带特性及信号完整性进行仿真分析。结果表明,与相同参数的Z型桥电磁带隙结构相比,当抑制深度为-30dB时,新型电磁带隙结构的同步开关噪声抑制带宽为130MHz～10．45GHz,相对带宽增加了58．8％,阻带下限截止频率降低了130MHz;同时使用差分线对传输信号时,新型电磁带隙结构电源平面较好地保持了信号的完整性。     

实时波前处理机中的同步开关噪声抑制

为解决自适应光学实时波前处理机中同步开关噪声问题,本文针对波前处理机电路特点,结合三维全波及电路仿真,对板上电源同步开关噪声来源进行了分析,并研究了去耦电容、分割电源平面及蘑菇型电磁带隙结构对噪声的综合抑制作用．研究结果表明,通过良好的器件布局、合理地进行电源平面分割及在关键器件周围加入去耦电容可降低平面间噪声,蘑菇型电磁带隙结构带宽高截止频率低的特性,具有良好的同步开关噪声抑制作用．针对实时波前处理机进行了仿真,采用系统级和板级噪声抑制措施后,在0～4GHz频带内噪声隔离度达到-52dB,满足处理机的电源完整性要求．     

一种具有新颖电磁带隙结构的印刷电路板电源平面

针对印刷电路板电源平面或地平面同步开关噪声的抑制问题,提出了一种新颖的二维电磁带隙结构.这一新颖设计基于用折线增加贴片的有效电感,单位晶格由折线、缝隙和正方形金属贴片桥接构建.结果表明,与相同参数的L形桥接电磁带隙结构比较,抑制深度为-30 dB时,新型二维电磁带隙结构的阻带宽度覆盖0.40 GHz到5.1 GHz的频率范围,相对带宽提高了约16.2%,阻带下限截止频率下降了200MHz,且具有全向抑制同步开关噪声以及采用标准印刷电路板工艺制作的优势.     

A novel two-layer compact electromagnetic bandgap (EBG) structure and its applications in microwave circuits

Recently, photonic bandgap (PBG) structures have become one of the most interesting areas of research. These structures consist of one-, two- or three-dimensional finite periodically perforated dielectric/metallic material or ground planes that forbid the propagation of all electromagnetic waves within a particular frequency band (called the bandgap). This property permits additional control over the behaviour of electromagnetic waves. The research work was originally done in optical region, …     

一种抑制同步开关噪声的微波光子晶体结构

为了确保抑制高速电路中同步开关噪声(SSN)的微波光子晶体(EBG)结构在兼顾带隙特性的同时,还具有良好的信号完整性,采用枝条绕转单元贴片的方法设计出一种新型EBG结构。利用HFSS软件对新型EBG结构抑制SSN的特性进行建模仿真,并制备刻蚀有新型EBG结构的4层印制电路板,用安捷伦矢量网络分析仪对其禁带特性进行测试,实验结果与仿真结果吻合良好。通过眼图对新型EBG结构进行的仿真分析显示,新结构的信号完整性良好。     

High-Gain and Low-RCS Patch Antenna Array Based on Slot-EBG Structure

A novel low radar cross-section (RCS) and high gain patch antenna array is proposed. A pair of slots introduced on the mushroom electromagnetic bandgap (EBG) patch realize polarization-dependency and act as parasitic radiation to enhance the antenna gain. A chessboard-like configuration composed of slot-EBG blocks is further equipped on the antenna array for scattering cancellation. Optimizing the layout pattern enables the designing of a high-gain and low-RCS antenna array using the slot-EBGs. Full-wave simulations validate that a front gain enhancement of more than 2.5.dB in the operating frequency band and low-RCS in a broad frequency band for normal incidence are obtained by the proposed antenna array.     

曲面EBG结构表面波带隙特性研究

对3种典型EBG结构在曲面上表面波带隙特性进行了研究。利用悬置微带线法,分析了曲面EBG结构带隙特性与其结构参数及曲率的关系。结果表明,曲率对表面波带隙的影响不是太明显,只是带隙中心频率有稍微的下降,介电常数与介质厚度对带隙影响规律与平面上一致。这一结论对在圆柱共形天线上应用高阻表面结构有一定的指导意义。     

一种新颖的缺陷地微带线低通滤波器

传统的微带线低通滤波器尺寸偏大,阻带较窄,针对此问题提出了一种新型微带线低通滤波器,该滤波器由半圆型缺陷地结构(S-DGS)单元和半圆型阶梯阻抗并联枝节(S-SISS)级联而成．分析了S-DGS和S-SISS的参数变化对其带阻特性的影响,建立了微带线滤波器的等效电路模型．该滤波器结构紧凑,3dB截止频率为2.7GHz,阻带为4~16GHz,比传统缺陷地结构滤波器阻带拓宽了20％．测试结果与仿真结果吻合较好,验证了所设计滤波器的可靠性．     

一种新颖的微带线低通滤波器

针对传统微带线低通滤波器尺寸偏大、阻带较窄的问题,本文提出了一种新型结构滤波器.该滤波器由半圆型缺陷地结构(Semicircle Defected Ground Structure,S-DGS)单元和圆型阶梯阻抗并联枝节(Circle stepped-impedance shunt stubs,C-SISS)组成.文中首先分析了S-DGS和C-SISS结构对微带线低通滤波器带阻特性的影响,接着给出了微带线滤波器的等效电路模型.该滤波器3 dB截止频率为2.7 GHz,阻带为4～15.0 GHz,比传统DGS滤波器阻带拓宽了20%.测试结果与仿真结果吻合较好,验证了所设计滤波器的可靠性.     

机载测控计算机的电磁兼容设计

以某机栽测控计算机为例,介绍了电磁兼容设计过程及主要的电磁干扰源和耦合途径;分析、预测了机载测控计算机工作的电磁环境及电磁兼容性;找出了干扰源,并针对不同干扰源提出了相应的电磁兼容设计方法;给出了某电路电磁兼容设计前后性能指标测试曲线。比较结果说明：机载测控计算机电磁兼容性设计合理,工作稳定可靠。该方法适用多种电子设备的电磁兼容设计。     

Impact of EBG Structures' Positions on the Performance of an EBG Antenna

Six circularly polarized patch antennas with electromagnetic band gap (EBG) arranged at different locations were studied. These EBG antennas were compared in terms of impedance bandwidth, axial ratio (AR) bandwidth and radiation patterns. When the EBG cells were placed closer to the edge of the substrate, the EBG antenna had a larger front radiation and a narrower bandwidth. Integrating the EBG cells closer to the center of the patch resulted in a wider impedance bandwidth, a wider axial ratio bandwidth and a decreased front gain.     

Improved quasi-static effective medium model of the electromagnetic band gap (EBG) high-impedance surface

For the complex electromagnetic property of the electromagnetic band gap (EBG) high-impedance surface, an improved quasi-static effective medium model is proposed, which makes a quantitative relationship among the geometry, medium properties and the electromagnetic properties of the EBG high-impedance surface. The macroscopic interaction of the wave with the EBG high-impedance surface is equivalent to that of the wave with an effective medium when the wavelength is large compared with the dimension of each cell of the high-impedance surface. With the effective medium model proposed by quasi-static electromagnetic theory, designs of the high-impedance surface and its application system such as antenna system can be implemented separately. Some numerical simulations and experiments of practical high-impedance surfaces are given to illustrate the applications and validity of the proposed model.     

Electromagnetic environments in roadways of underground coal mines and a novel testing method

The electromagnetic environment of laneways in underground coal mines is an important area for the design of new electronic products,as well as a fundamental space for mine monitoring,surveillance,communications and control systems.An investigation of electromagnetic interference in coal mines is essential for the enhancement of performances of these systems.In this study,a new field method is provided in which radiated emission tests in coal mine laneways have been carried out.We conclude that:1) the wiring motor vehicles can radiate interference with a bandwidth up to 1 GHz and with an amplitude 10 dBμV/m higher than the background noise;2) the PHS (Personal Handy phone System) mobile communication system can cause interference 40 dBμV/m higher than the background noise;3) an interference 25 dBμV/m higher than the background noise can be generated during the communication at a working bandwidth of 48.8 MHz;and 4) power cables,battery vehicles as well as mechanical and electrical dong rooms have little effect on the electromagnetic radiation environment in coal mine tunnels.     

传导性EMI噪声的智能处理及参数建模研究

针对现阶段大量的传导性电磁干扰问题仍不断出现且尚未得到很好地解决的现象,对传导性电磁兼容进行了综合技术研究,提出传导性电磁干扰噪声诊断与抑制一体化的智能处理系统,将软件设计与硬件设计相结合,对噪声进行相应的处理.同时对传导噪声智能处理系统进行参数建模,给出将技术解决方案与经济成本优化联系在一起的综合数学模型和设计指导方法.同时给出建模后的测试装置和相关实例,并对实际测量的数据进行了实验对比,结果表明该系统能有效解决电源线上的EM I噪声的干扰问题.     

软接触结晶器连铸的电磁计算与实验分析(Ⅱ)

结合软接触结晶器连铸过程的准三维电磁场数值模拟和实验室中锡等金属的软接触结晶器连铸实验,研究了电磁场频率、铸坯电物性、感应圈电流等对铸坯电磁力和表面电磁压力的作用关系,给出了部分理论计算和实验室连铸实验所得的数学模型－ 研究表明,软接触结晶器连铸中,铸坯表面的电磁力与电磁场频率成对数抛物型函数关系,与感应圈电流成抛物型函数关系,铸坯表面的振痕深度为普通连铸的１０ ％ ,并磁感应强度越高则振痕越浅,其无量纲平均深度与无量纲磁感应强度成误差补函数关系     

屏幕泄漏信息最佳截获频段的一种选取方法

计算机显示系统辐射发射出含有屏幕信息的电磁波,在远场用接收机可隐秘截获. 为了快捷有效地找出截获屏幕信号的最佳频段,提出了一种基于通用设备的方法. 首先,在个人计算机关机及开机且显示特制黑白竖条纹图像情况下分别多次测量10 MHz~1 GHz频段的频谱,通过频谱相减判断出极可能含有屏幕信息的大致频段;然后,在点频及其谐波频点附近查找特制图像信号,若显示全黑图像时此峰值信号消失则可判断其为特制图像信号;最后,综合考虑频点处特制图像信号峰值大小和背景电磁噪声,挑选出最佳截获频段. 截获实验结果表明,所选频段可还原出最佳屏幕图像.     

Study on ceramic photonic bandgap structure with three-dimensional diamond lattice

A novel process, which was based on powder injection molding, was investigated for the fabrication of ceramic photonic bandgap structure with three-dimensional diamond lattice. The SiO2-TiO2 ceramic powder was mixed with a water-soluble agent to produce slurry. The slurry was then injected into an epoxy mold with inverse diamond lattice, fabricated by the stereolitographic rapid prototyping process. To increase the density of the green compact, cold isostatic pressing was applied on the unit. Using thermal debinding, the water-soluble agent and the epoxy were extracted at 360 and 650 K, respectively. Sintering was immediately done at 950 K for 5 h and the desired three-dimensional ceramic structure was obtained. The calculated band diagram for this structure indicated the existence of an absolute photonic bandgap for all wave vectors. At 14.7-18.5 GHz, a complete band gap was located with a maximum attenuation of 30 dB at 17 GHz, when transmission was measured in the 〈100〉 direction between 10 and 20 GHz.     

Analysis of reflection characteristics for foam filled grid structure

The reflection characteristics of gird structures are calculated by the spatial network method in the case of normal incidence plane electromagnetic wave. The numerical result shows that the grid panels without electromagnetic wave absorbing foams are not ideal. However, the absorbing ability can be achieved as low as -25 dBsm from 8 GHz to 12 GHz when the grid cells are filled with foam absorbers. Also it is noted from computation that the foam filled grid structures with larger cell size, higher and thinner ribs will improve the absorbing abilities, which illustrates that they can be used as the effective light-weight stealth structures for aeronautical application.     

用于生化分析的聚二甲基硅氧烷微混合器

对一种电磁式微腔体混合器的设计、制作及实验进行了研究。从提高其混合性能出发,对混合器进行了动力学分析,得出了适于快速混合的振动模式。结果表明,混合效果是由驱动频率及振幅共同决定的。利用模压工艺制作出适于光学探测的聚二甲基硅氧烷(PDMS) 混合器。利用DE-LIGA工艺制作出的平面线圈,具有结构紧凑,不易脱落等优点。设计的微混合芯片由PDMS混合器、永磁体、光学透镜、平面线圈、微型光谱仪等混合集成,并对振动膜厚度为50 μm的φ6 mm混合器进行定量检测,当混合量为150μL时,动态混合能在5 s内完成。