成渝中同轴电缆业务Щ支路工频及广播干扰整治

成渝中同轴电缆业务Щ支路工频及广播干扰，主要由传输线受外界工频及广播电流产生的干扰电势，特别是部分纵向电势向横向电势转化而产生，可采用电桥法、脉冲测试、探测法等，对中继、巡房电缆进行细致的测试，查出由于导线引线错接而成为鸳鸯线，破坏了线对的扭绞，导线接地使导线纵向电势分布发生变化，增大了磁敏感系数，必须采取高屏蔽电缆、消除线对扭绞和线路地气等进行整治。     

成渝中同轴电缆业务Щ支路工频及广播干扰整治

成渝中同轴电缆业务Щ支路工频及广播干扰，主要由传输线受外界工频及广播电流产生的干扰电势，特别是部分纵向电势向横向电势转化而产生，可采用电桥法、脉冲测试、探测法等，对中继、巡房电缆进行细致的测试，查出由于导线引线错接而成为鸳鸯线，玻坏了线对的扭绞，导线接地（地气）使导线纵向电势分布发生变化，增大了磁敏感系数。必须采取高屏蔽电缆、消除线对扭纹和线路地气等进行整治。（ｅｄ）     

导线转接工艺方法研究

主要针对低频电缆的数量、规格变化或延长,进行了导线转接工艺方法研究.在导线转接试验的基础上,明确了转接原则和转接类型,提出了转接工艺要求,介绍了多种导线转接工艺方法及转接接头检验方法.重点研究了普通导线和屏蔽导线、单根导线和多根导线的转接方法,采用转接套管的方法较传统方法更具可靠性,且有效地提高了电缆组件的信息传输和电磁兼容,确保了产品质量.     

双扭线带状电缆的穿刺压接

编织或胶接的双扭线带状电缆有优良的电气性能,但以往常用焊接方法端接。现已设计成一种端接装置,可使离散导线、双扭线带状电缆与“U”形簧片连接器实现穿刺压接,以保证其可靠性和低成本。     

电子设备屏蔽与接地 典型元件的屏蔽方法

一、导线的屏蔽 1、概述当一个设备分成各自屏蔽的几个分机或若干个部件时,它们之间必须有导线或高频电缆连接,以避免导线辐射而造成对外界的干扰或从外界接收干扰噪声,从而形成部件分机工作不稳定。用于传输信号的传输线有双线传输线、同轴传输线及波导传输线等。 2、导线的几种耦合形式①导线间的电容性耦合由于两导线间存在着电容性耦合,导线与地间存在有噪声电压。如果不将两导线距     

水对室内线缆的影响

1.腐蚀严重时浸水线缆中的导线可能会断路。用于线缆的塑料和所有其他塑料材料一样都有微孔。水可透过线缆外皮渗入线缆。有电流时,工作线对间会产生电势差,水渗透有微孔的塑料绝缘体与导体接触,电子会通过导电的水移动。一段时间后,水会变成一种稀硫酸溶液,导线的铜芯和外镀层之间将产生电解作用,从而腐蚀铜芯部分,导致断路。2.电容和衰减电容是指有电势差时电缆导体之间绝缘材料储存电荷的能力。电缆电容越小,信号传输质量就越好。因电容会随电缆长度增大而增大,所以电缆的电容越小,信号传输距离就越长。电容和电阻一样都是电缆固有的特性…     

激光剥线器比其他剥线钳既快又好

和传统的剥线钳及其他的激光剥线器比较，一种新的激光剥线器可望降低运行成本，并改进加工工艺。由通用激光公司制造的Lasermatic剥线器可对4 in宽的扁平带状电缆进行剥皮，同时也可对直径为0.02到0.3 in的圆形导线皮。有一种型号的剥线器还可剥去ML聚酰亚胺磁性导线的绝缘层,已证明其他剥线器是很难做到这一点的。     

电线、电缆、护套

0210355市话电缆混线故障查找方法的探讨〔刊〕/董西强//光纤与电缆及其应用技术.-2001,(6).-35～38(D) 主要叙述市话电缆混线故障的判定方法及所产生的原因,提出了生产过程不同工序间绝缘不良故障的解决方案。     

电子设备互连电缆的电磁耦合数值结果分析

电子设备中不同类型的信号电缆密集敷设,容易产生电磁干扰问题。大多数电缆间电磁耦合现象发生在同一束或邻近的电缆之间。这种耦合途径通常分布参数模型来描述,并用电路理论来简化。电子设备内各模块间互连电缆以及模块内PCB印制线间的距离较小,相互间干扰主要属于近场感应耦合。互连电缆间的感应耦合主要指通过线间的电容C及互感M而形成电场耦合和磁场耦合的两种耦合形式。两导线间的电场耦合和磁场耦合的模型图见图1、图2：     

传声器电缆线检测器

对于经常使用的传声器,其电缆线有时会发生故障,并为不能迅速排除而苦脑。这里介绍一种结构简单、制作容易的传声器电缆线检测器。使用时,将传声器电缆线的输入输出端插好,分别按动按钮开关。若二极管发亮,表示导线完好。若不亮则表示有毛病。     

Calculation of the characteristics of two-wire lines in multiconductor cables

A rigorous method is proposed for calculating the parameters of two-wire lines (twisted pairs) surrounded by a single metal shield and the mutual coupling between these lines. It is shown that coupling between the lines in multiconductor cables results in electromagnetic interference (crosstalk) in communications channels and that inphase currents in the lines are caused by the asymmetry of excitation and loads. The stray voltages induced across the impedances placed at the beginning and the end of an adjacent line are determined at a given power in the main line. The effect produced by the loads placed between the wires and the shield is considered. The proposed method allows generalization of the obtained results to the case of lossy multiconductor cables.     

FDTD modeling of common-mode radiation from cables

Radiation from cables attached to printed circuit boards and shielding enclosures is among the primary concerns in meeting FCC Class A and B limits. The finite-difference time-domain (FDTD) method can be employed to model radiation from printed circuit boards and shielding enclosures with complex geometries, but difficulties in modeling wires and cables of arbitrary radii are encountered. Modeling the wire by setting the axial component of the electric field to zero in the FDTD method results in an effective wire radius that is determined by the mesh discretization. Neglecting the wire radius in applications, such as electromagnetic interference (EMI) or printed circuit board modeling, may result in gross errors because near-field quantities are typically sensitive to wire thickness. Taflove et al. (1988) have developed a subcellular FDTD algorithm for modeling wires that has been shown to work well for plane wave scattering. The method uses a quasistatic field approximation to model wires with a well defined radius independent of the mesh dimensions. The wire model is reviewed and investigated for application to common-mode radiation from cables attached to printed circuit boards, where the source is often a noise voltage at the connector. Also investigated is energy coupling to attached cables through enclosure apertures resulting in common-mode radiation from the cable. The input impedance for a center-fed dipole antenna, as well as a monopole connected to a conducting half-sheet, is computed with FDTD methods and compared to moment method input impedance results. A simulation of a shielding enclosure with an attached cable demonstrates the utility of FDTD analysis in modeling common-mode radiation     

局用射频线缆在工程中的应用

简要介绍局用射频线缆的应用情况、线缆的选型、常用线缆型号及指标 ，最后提出了在工程设计中，应充分考虑原有线缆及拟用线缆的电气指标、物理性能、应用场合等多种因素。     

卫星地球站瞬变电压干扰的影响与防护

瞬变电压是指在很短的时间内电压偏离正常电压电平的现象。由于卫星地球站系统内部各种信号电线电缆之间存在的磁场相合会产生瞬变电压干扰,严重时会引起卫星地球站系统网络通信故障。文章对卫星地球站瞬变电压干扰的产生和影响进行了分析和研究,进而总结出可以采用的防护措施。     

移动通信基站出入缆线的防雷措施

简介移动通信基站出入缆线引入雷害的主要原因,并对基站出入缆线的防雷问题提出具体措施。     

High frequency cable connector for twisted pair cables

A new cable connector for twisted pair cable usable for high frequency applications is presented in this paper. An elastic conductive matrix as an interface between cable and printed wiring board (PWB) is pressed against the ends of the copper wires of the cable, and a land grid array on the PWB, thereby making the connections. The shielding braid of the cable is lengthened by a tube structure up to the same plane as the end of the copper wires, where the shielding is connected to an earth plane on the PWB. This not only gives a sound basis for good electromagnetic interference (EMI) behavior, but can also serve as an adequate structure for a dc barrier of common-mode currents in the shielding of twisted pair cables. A washer-formed capacitor between the earth of the PWB and the shielding tube structure would probably be the only addition needed. Measurements, performed on two connectors and the connected twisted pair cable, confirmed the hypothesis of how the performance of the new cable would be improved in the high frequency range compared to the SOFIX cable connector.     

Prediction of Crosstalk in Ribbon Cables: Comparison of Model Predictions and Experimental Results

The prediction of crosstalk in ribbon cables is investigated. Experimental results are obtained for a 20-wire ribbon cable and compared to the predictions of the multiconductor transmission line (MTL) model. Based on the experimental configuration tested, it would appear that accurate predictions of crosstalk can be achieved in these controlled-characteristic cables. The prediction accuracies are typically within ±1 dB for frequencies such that the line is electrically short and ±6 dB for frequencies such that the line is electrically long. It was found that the parasitic wires in the cable can have a significant effect (as much as 40 dB) on the coupling between a generator circuit and a receptor circuit in the cable. Therefore, to achieve accurate predictions in ribbon cables, one must consider the interactions between all wires in the cable. The wire insulation evidently cannot be ignored for frequencies such that the line is electrically long. The impedance of the reference wire cannot be ignored for low frequencies where the common-impedance coupling dominates the electromagnetic-field coupling.     

电子设备互连电缆电磁兼容性预测与分析

电子设备互连电缆之间的电磁耦合是降低电子设备电磁兼容性的重要原因.本文在提出电子设备互连电缆间的电磁耦合模型的基础上,利用场路结合的方法对电子设备互连电缆进行了电磁耦合预测分析.数值分析结果对最终实现电子设备的电磁兼容性有重要的指导意义.     

浅谈电线电缆用防护套

鉴于目前用户对电线电缆用防护套的需求不断增加,对使用性能要求不断提高,对电线电缆用芳纶纤维防护套、硫化防护套、PET(聚对苯二甲酸乙二酯)伸缩防护套、尼龙66伸缩防护套的材料和性能特点与应用进行了详细介绍。     

Present status and outlook of line transmission systems in China

The various line transmission media, including open wires, symmetrical pair cables, coaxial cables, and optical fiber cable, that are used in the different regions of China are described. Both analog transmission systems and the newer digital transmission systems are discussed. The standardized physical transmission media deployed throughout China-symmetrical pair cables, coaxial cables, and optical fiber cables-are also discussed