1、BS EN 50289-1-11:2016Communication cables Specifications for test methodsPart 1-11: Electrical test methods Characteristic impedance, input impedance,return lossBSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS EN 50289-1-11:2016 BRITISH STANDARDNational forewordThi
2、s British Standard is the UK implementation of EN 50289-1-11:2016. It supersedes BS EN 50289-1-11:2002 which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee EPL/46, Cables, wires and waveguides, radio frequency connectors and accessories for communication an
3、d signalling.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2017. Published
4、 by BSI Standards Limited 2017ISBN 978 0 580 93206 9 ICS 33.120.01 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 January 2017.Amendments/corrigenda issued s
5、ince publicationDate Text affectedBS EN 50289-1-11:2016EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 50289-1-11 December 2016 ICS 33.120.20 Supersedes EN 50289-1-11:2001 English Version Communication cables - Specifications for test methods - Part 1-11: Electrical test methods - Characteristi
6、c impedance, input impedance, return loss Cbles de communication - Spcifications des mthodes dessai - Partie 1-11: Mthodes dessais lectriques - Impdance caractristique, impdance dentre, affaiblissement de rflexion Kommunikationskabel - Spezifikationen fr Prfverfahren - Teil 1-11: Elektrische Prfverf
7、ahren - Wellenwiderstand, Eingangsimpedanz, Rckfludmpfung This European Standard was approved by CENELEC on 2016-09-05. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard wit
8、hout any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CENELEC member. This European Standard exists in three official versions (English, French, German). A version in any o
9、ther language made by translation under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cy
10、prus, the Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
11、the United Kingdom. European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2016 CENELEC All rights of exploitation in any form and by any
12、 means reserved worldwide for CENELEC Members. Ref. No. EN 50289-1-11:2016 E BS EN 50289-1-11:2016Contents Page European foreword 4 1 Scope 5 2 Normative references 5 3 Terms and definitions 5 4 Test method for mean characteristic impedance (S21type measurement) 10 4.1 Principle 10 4.2 Expression of
13、 test results . 10 5 Test method for input impedance and return loss (S11type measurement) 10 5.1 Method A: measurement of balanced cables using balun setup 10 5.1.1 Test Equipment 10 5.1.2 Test sample 11 5.1.3 Calibration procedure . 11 5.1.4 Measuring procedure . 12 5.2 Method B: measurement of ba
14、lanced cables using balun-less setup . 12 5.2.1 Test Equipment . 12 5.2.2 Test sample . 13 5.2.3 Calibration procedure . 13 5.2.4 Measuring procedure . 13 5.3 Method C: measurement of coaxial cables . 14 5.3.1 Test Equipment . 14 5.3.2 Test sample . 14 5.3.3 Calibration procedure . 14 5.3.4 Measurin
15、g procedure . 15 5.4 Expression of test results . 15 6 Test report 17 Annex A (normative) Function fitting of input impedance . 18 A.1 General . 18 A.2 Polynomial function for function fitting of input impedance 18 A.3 Fewer terms . 19 Annex B (normative) Correction procedures for the measurement re
16、sults of return loss and input impedance 21 B.1 General . 21 B.2 Parasitic inductance corrected return loss (PRL) 21 B.3 Gated return loss (GRL) 23 B.4 Fitted return loss (FRL) . 25 B.5 Comparison of gated return loss (GRL) with fitted return loss (FRL) 31 EN 50289-1-11:2016 (E)BS EN 50289-1-11:2016
17、B.6 Influence of the correction technique on return loss peaks . 32 Annex C (normative) Termination loads for termination of conductor pairs . 35 C.1 General . 35 C.2 Verification of termination loads 36 Bibliography . 37 EN 50289-1-11:2016 (E)BS EN 50289-1-11:2016European foreword This document EN
18、50289-1-11:2016 has been prepared by CLC/TC 46X “Communication cables“. The following dates are fixed: latest date by which this document has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2017-09-05 latest date by which the national stan
19、dards conflicting with this document have to be withdrawn (dow) 2019-09-05 This document supersedes EN 50289-1-11:2001. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CENELEC and/or CEN shall not be held responsible for identifyi
20、ng any or all such patent rights. EN 50289-1-11:2016 (E)BS EN 50289-1-11:20161 Scope This part of EN 50289 details the test methods to determine characteristic impedance, input impedance and return loss of cables used in analogue and digital communication systems. It is to be read in conjunction wit
21、h EN 50289-1-1, which contains essential provisions for its application. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated refer
22、ences, the latest edition of the referenced document (including any amendments) applies. EN 50289-1-1:2001, Communication cables - Specifications for test methods - Part 1-1: Electrical test methods - General requirements EN 50289-1-5:2001, Communication cables - Specifications for test methods - Pa
23、rt 1-5: Electrical test methods - Capacitance EN 50289-1-7:2001, Communication cables - Specifications for test methods - Part 1-7: Electrical test methods - Velocity of propagation EN 50290-1-2, Communication cables - Part 1-2: Definitions 3 Terms and definitions For the purposes of this document,
24、the terms and definitions given in EN 50290-1-2 and the following apply. 3.1 characteristic impedance ZC(wave) impedance at the input of a homogeneous line of infinite length. The characteristic impedance Zcof a cable is defined as the quotient of a voltage and current wave which are propagating in
25、the same direction, either forwards or backwards. frCfruuZii= =(1) where Zcis characteristic impedance; uf,ris voltage wave propagating in forward respectively reverse direction; if,ris current wave propagating in forward respectively reverse direction. EN 50289-1-11:2016 (E)BS EN 50289-1-11:20163.2
26、 mean characteristic impedance Zcmin practice for real cables which always have structural variations the characteristic impedance is described by the mean characteristic impedance which is derived from the measurement of the velocity of propagation (EN 50289-1-7) and the mutual capacitance (EN 5028
27、9-1-5). However, this method is only applicable for frequencies above 1 MHz and non-polar insulation materials (i.e. materials having a dielectric permittivity which doesnt change over frequency). The mean characteristic impedance approaches at sufficiently high frequencies (100 MHz) an asymptotic v
28、alue ZThe characteristic impedance may be expressed as the propagation coefficient divided by the shunt admittance. This relationship holds at any frequency. ( )c1 tanjZjjC j C Ca a += (2) where Zcis complex characteristic impedance (); is attenuation coefficient (Np/m) ; is phase constant (rad/m);
29、tan is loss factor; is circular frequency (s-1); C is mutual capacitance (F/m). At high frequencies, where the imaginary component of impedance is small, and the real component and magnitude are substantially the same we get for the mean characteristic impedance pcm1ZC C vC=(3) Where Zcmis mean char
30、acteristic impedance (m); v is velocity of propagation (m/s); pis phase delay (s/m); C is mutual capacitance (F/m). 3.3 terminated input impedance Zinimpedance measured at the near end (input) when the far end is terminated by a load resistance of value equal to the system nominal impedance ZREN 502
31、89-1-11:2016 (E)BS EN 50289-1-11:20163.4 open/short input impedance ZOSimpedance measured at the near end (input) when the far end is terminated with its own impedance. In practice this is the case when the round trip attenuation is greater than 40 dB at any measured frequency. This property takes i
32、nto account structural variations in the cable. For samples with lower round trip loss it is determined by the open/short circuit method: os open shortZ ZZ= (4) where Zosis input Impedance of the cable obtained from an open/short measurement; Zopenis impedance with an open circuit at the far end of
33、the cable; Zshortis impedance with a short circuit at the far end of the cable. 3.5 fitted characteristic impedance Zfitis obtained from a least square error function fitting of the open/short input impedance. The fitting can be applied on the magnitude, real and imaginary part of the input impedanc
34、e. The fitted characteristic impedance is an alternative to the mean characteristic impedance to describe the characteristic impedance. It is only valid if the variations with frequency of the input impedance around its characteristic impedance are balanced. 3.6 (operational) return loss RL (operati
35、onal) return loss is measured at the near end (input) when the far end is terminated by a load resistance of value equal to the system nominal impedance ZR. It quantifies the reflected signal caused by impedance variations. The (operational) return loss takes into account the structural variations a
36、long the cable length and the mismatch between the reference impedance and the (mean) characteristic impedance of the cable (pair). If the (mean) characteristic impedance of the cable (pair) is different from the reference impedance, one gets, especially at lower frequencies (where the round trip at
37、tenuation is low), multiple reflections that are overlaid to the structural and junction reflections. Therefore, return loss RL is also referenced as operational return loss. As an example, Figure 1, shows the operational return loss under different conditions. The blue line shows the return loss of
38、 a pair having a characteristic impedance equal to the reference impedance but taking into account that the impedance is varying with frequency (see right-hand graph). The red line shows the return loss of a pair having a characteristic impedance that is different from the reference impedance (110 v
39、s. 100 ). For both lines, periodic variations that are caused by multiple reflections between the junctions at the near and far end are observed. The green line shows a simulation of a pair having a frequency independent characteristic impedance which is equal to the reference impedance. EN 50289-1-
40、11:2016 (E)BS EN 50289-1-11:2016051015202530354045500,1 1 10 100dBMHzReturn LossRL w/o mismatchRL w mismatchRL w/o mismatch; Zc frequency independentRL RL RL -0,2-0,16-0,12-0,08-0,0400,040,080,120,160,20,80,840,880,920,9611,041,081,121,161,20,1 1 10 100MHzfrequency dependent factor of the characteri
41、stic impedanceRealImagFigure 1 Return loss with and without junction reflections 3.7 open/short return loss OSRL way to avoid in the measurement of return loss multiple reflections due to a mismatch between the characteristic impedance (asymptotic value at high frequencies) of the CUT and the refere
42、nce impedance is to use a CUT terminated in its nominal impedance and having a very long test length such that the round trip attenuation of the CUT is at least 40 dB at the lowest frequency to be measured. For standard LAN cables, this would result in a CUT length of roughly 1 000 m for the lowest
43、frequency of 1 MHz. Another way (when long CUT length is not available) is to measure the characteristic impedance (open/short method) and to calculate the return loss. As the characteristic impedance is obtained from the measurement of the open and short circuit impedance, it is proposed to name su
44、ch obtained return loss open/short return loss. This open/short return loss includes the effect of structural variations and the mismatch at the near end (including the effect due to a frequency-dependent characteristic impedance), but it does not take into account multiple reflections. Figure 2 sho
45、ws the difference between operational return loss and open/short return loss. The left-hand graph shows the results of a pair having a characteristic impedance which is different from the reference impedance (110 vs. 100 ). The right-hand graph shows the results of a pair having a characteristic imp
46、edance which is equal to the reference impedance (100 ). One may recognize that the open/short return loss does not take into account multiple reflections. 051015202530354045500,1 1 10 100dBMHzReturn LossRL w mismatchOSRL w mismatchRL OSRL 051015202530354045500,1 1 10 100dBMHzReturn LossRL w/o misma
47、tchOSRL w/o mismatchRL OSRL Figure 2 Return loss and open/short return loss EN 50289-1-11:2016 (E)BS EN 50289-1-11:20163.8 structural return loss SRL The structural return loss is the return loss where only structural variations along the cable are taken into account. The mismatch effects at the inp
48、ut and output of the transmission line (including the effect due to a frequency-dependent characteristic impedance) have been eliminated. The structural return loss cannot be measured directly but is calculated from the measurement of the characteristic impedance (open/short method). OSOSfitfit20 lg
49、ZZSRLZZ= +(5) where ZOSis the (complex) input impedance obtained from the measurement of the open and short circuit impedance; Zfit is the (complex) characteristic impedance obtained from a curve fitting of the real and imaginary part of ZOS. The left-hand graph of Figure 3 shows the operational return loss, open/short return loss and structural return loss of a CUT having a characteristic impedance of 110 . A difference between both is observable. The operational return loss takes into account all
