同轴电缆转移阻抗测量方法

Ⅰ 请高手帮忙翻译

屏蔽效率测量
Measurement of Shielding Effectiveness
屏蔽效率是评价射频电缆屏蔽性能的重要参数，属于电磁兼容的范畴。近年来，随着欧盟CE强制安全认证的开展、,电缆的屏蔽效率越来越受到人们的关注判闹。
Shielding effectiveness is an important parameter for evaluating Radio-Frequency coaxial cable's shielding performance, belonging to the category of EMC. Recently with the concting of mandatory CE certification in European Union, the shielding effectiveness is paid more and more attentions.
屏蔽效率主要有以下几种测量清圆方法：三同轴法、吸收钳法、线注入法、GTEM Cell小室法。其中三同轴法可以测掘正罩量电缆的转移阻抗、耦合损耗、屏蔽衰减等；吸收钳法可以测量电缆的屏蔽衰减；线注入法可以测量电缆的耦合损耗；GTEM Cell可以测量电缆的屏蔽衰减。
The commonly used methods to measure shielding effectiveness of RF coaxial cable are triaxial method, absorbing clamp method, wire injection method, and GTEM cell method. Of which triaxial method can be used to measure the transfer impedance, coupling loss, screening attenuation, etc. of cables; absorbing clamp method can be used to measure the screening attenuation of cables; wire injection method can be used t measure the coupling loss of cables; and GTEM cell method can be used to measure the screening attenuation of cables.
屏蔽效率的几个参数定义如下：
The definitions for the parameters about shielding effectiveness are as follows:
1．屏蔽衰减定义为沿电缆屏蔽层单位长度测得的电压与内导体通过的电流之比。
1. Screening attenuation is defined as the ratio of the voltage measured along the unit length of cable shield layer to the current passing through the inner conctor.
2．耦合损耗定义为线缆的输入功率与远端或和近端耦合功率较大值的对数比（对于同轴电缆，其等于屏蔽衰减）。
2. Coupling loss is defined as the logarithmic ratio of the input power of the cable to the coupling power, which got the maximum effect of either near or far end. (for coaxial cables, it equals to screening attenuation).
3．屏蔽衰减定义为线缆的输入功率与最大辐射功率的对数比,可以被认为是一个电气长度比较长的电缆的屏蔽效率。
3. Screening attenuation is defined as the logarithmic ratio of the input power of the cable to the radiated maximum peak power, it can also be considered as a electrically long cable's shielding effectiveness.

Ⅱ 求qindajia帮忙翻译

表面转移阻抗（三同轴档喊法）测量
目前，对于屏蔽对称电缆和屏蔽多芯等类似于同轴电缆的表面转移阻抗测量国内还未有标准，IEC 62153-4-3:2002 电磁兼容——表面转移阻抗（三同轴测量方法）及EN 50289-1-6:2002 转移阻抗（三同轴测量方法）是一种既可以测量同轴电缆又可以测量类同轴的屏蔽对称和屏蔽多芯电缆的转移阻抗试验方法。IEC 62153-4-3:2002有测试方法A（匹配-短路法）和测试方法B（短路-短路法）两种，其中测试方法A与EN 50289-1-6:2002测量方法完全相同。本文介尘饥绍的是IEC 62153-4-3:2002测试方法A的内容。该方法在100MHz频率以下测量无须在屏蔽室内进行，且测量较为方便。
1．转移阻抗ZT的定义
一个短电气长度的纵向均衡屏蔽的转移阻抗ZT定义为单位长度上由被测的屏蔽及测量夹具形成的，在匹派蠢返配外电路上感应的纵向电压U2和馈入内电路的电流I1之比。反之亦然。
2．转移阻抗的测试方法
通过测量在三同轴装置中的电缆来测定电缆的转移阻抗。试样电缆的屏蔽和内导体组成内电路，电缆屏蔽和同轴测试夹具组成外电路，且内电路即电缆终端是匹配的，外电路的近端即电缆屏蔽的近端是短路的，远端连接到接收机。
Surface transfer impedance (3 coaxial) measuring
At present, the shielded cable and shielded symmetrical multi-core and other similar surface transfer impedance of coaxial cable not a standard measure of domestic, IEC 62153-4-3:2002 Electromagnetic Compatibility - Surface transfer impedance (three coaxial measurement method) and EN 50289-1-6:2002 transfer impedance (3 coaxial measurement method) is a measurement of both coaxial cable and can measure type coaxial shielded symmetrical and shielded multi-core cable transfer impedance test method. IEC 62153-4-3:2002 a test method A (match - short-circuit method) and test method B (short - short-circuit method), with which test methods A and EN 50289-1-6:2002 exactly the same measurement methods. This article describes the test method A, IEC 62153-4-3:2002 content. This method is not measured in the 100MHz frequency of the following conct in a shielded room, and the measurement is more convenient.
1. The definition of transfer impedance ZT
A short length of the longitudinal electric shield transfer impedance ZT balanced is defined as the unit of length measurement by the DUT fixture shielding and the formation, the way in matching foreign longitudinal voltage sensor and fed into the U2-circuit ratio of the current I1. And vice versa.
2. Transfer impedance test method
By measuring the device in three coaxial cables to determine the transfer impedance of cables. Sample cable shield and inner conctor within the circuit component, coaxial cable shield and the composition of the external circuit test fixture, and the cable terminal is within the circuit that matches the external circuit that is proximal to the proximal shield cable is short, and remote connected to the receiver.

Ⅲ 电缆屏蔽效率db是什么

屏蔽性能指标介绍

1.表面转移阻抗(SuRFaceTransferImpedance)

按IEC61196-1测试同轴电缆的方法，测试带屏蔽的平衡电缆，短路8根芯线后用50Ω信号源激励。被测试线长1米，测试频率30MHz，频率越高，线长越短导体表面转移阻抗。主要用于评估连接硬件的屏蔽效率，其实测值不超过以下计算值。

ZTcable=37+4f+4f1/2+5f1/3

ZTcable：表面转移阻抗，单位mΩ/m f：信号频率，单位MHz

2.转移阻抗(TransferImpedance)

转移阻抗与屏蔽电缆和连接硬件的屏蔽效率相关，其数值可通过实验室高频密封箱测量屏蔽插入损耗，计算得出。

屏蔽性能指标介绍

1.表面转移阻抗(SuRFaceTransferImpedance)

按IEC61196-1测试同轴电缆的方法，测试带屏蔽的平衡电缆，短路8根芯线后用50Ω信号源激励。被测试线长1米，测试频率30MHz，频率越高，线长越短导体表面转移阻抗。主要用于评估连接硬件的屏蔽效率，其实测值不超过以下计算值。

ZTcable=37+4f+4f1/2+5f1/3

ZTcable：表面转移阻抗，单位mΩ/m f：信号频率，单位MHz

2.转移阻抗(TransferImpedance)

转移阻抗与屏蔽电缆和连大竖接硬件的屏蔽效率相关，其数值可通过实验室高频密封箱测量屏蔽插入损耗，计算得出。

Ri1=Ri2=50Ω——网络分析仪特性阻抗 R1=50Ω——馈电电阻 R2=50Ω——终端电阻 U1=信号发射电压(V) U2=信滚谨大号接收电压(V) Uc=被测设备两端电压 Zcond=连接器特性阻抗(Ω) Zt=转移阻抗(Ω)

Zt=1/l电缆长度•Ri1/Ri2•(R2+Ri2)•U2/U1=100/l电缆长度•U2/U1 由于屏蔽插入损耗(αs)为20•lg(U2/U1)dB，转移阻抗(Zt)也可以表示为： Zt=100•10α/20(Ω)

3.耦合衰减(CouplingAttenuation)

耦合衰减用于描述电缆系统的电磁兼容性能。耦合衰减Catt=Pr/Pi(Pr：线缆接收功率;Pi：在内导体上产生的噪声功率)

将电缆近似看作电磁场中的全向天线，其接收到的电磁功晌键率Pr=λ2/4π•PD(λ：信号波长，PD：电磁场功率密度) .

Ⅳ 同轴电缆阻抗如何测量

用DTX－1800的测试仪器，在基准中选中同轴电缆就进行测试，然后查看一下标准就好了。

Ⅳ 什么是转移阻抗啊,为什么说同轴电缆可以提供一个最大的电缆转移阻抗

在复杂电力系统中只保留发电机电动势节点（包含无限大功率母线）和短路点，经过网络化简消去其他中间世弊节点（或称联络节点），最后得到一个网络。在此网络中，可以略去各电源间的搜租族连线，以为连线中的电流是电源间的交换电流，与短路电流无关。这样就形成了一个以短路点为中心的辐射形网络，每一条辐射支路只含一个电源，经一阻抗（称转移阻抗）与短路点相连。 简单的说，电源的转移阻抗就型顷是电源到电路短路点阻抗，多用于短路计算。

Ⅵ 如何用同轴电缆本身的性质计算特性阻抗

然而在计算机网络中，“宽带电缆”却指任何使用模拟信号进行传输明判的电缆网。 (1)同轴电缆的特搏凯性阻抗 同轴电缆的平均特性阻基槐唤抗为50±2Ω,沿单根同轴电缆的