1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationElectromagnetic compatibility Emission measurements in fullyanechoic chambersPD CLC/TR 50485:2010National forewordThis Published Document is the UK implementation of CLC/TR 50485
2、:2010. Itsupersedes PD CR R210-010:2002 which is withdrawn.The UK participation in its preparation was entrusted by Technical CommitteeGEL/210, EMC - Policy committee, to Subcommittee GEL/210/12, EMC basic,generic and low frequency phenomena Standardization.A list of organizations represented on thi
3、s committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisions of acontract. Users are responsible for its correct application. BSI 2010ISBN 978 0 580 64296 8ICS 33.100.10Compliance with a British Standard cannot confer immunity froml
4、egal obligations.This Published Document was published under the authority of theStandards Policy and Strategy Committee on 30 June 2010.Amendments issued since publicationAmd. No. Date Text affectedBRITISH STANDARDPD CLC/TR 50485:2010TECHNICAL REPORT CLC/TR 50485 RAPPORT TECHNIQUE TECHNISCHER BERIC
5、HT March 2010 CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: Avenue Marnix 17, B - 1000 Brussels 2010 CENELEC - All rights of exploitation in any form and by any mea
6、ns reserved worldwide for CENELEC members. Ref. No. CLC/TR 50485:2010 E ICS 33.100.10 Supersedes R210-010:2002English version Electromagnetic compatibility - Emission measurements in fully anechoic chambers Compatibilit lectromagntique - Emission en chambres anchoques entiers Elektromagnetische Vert
7、rglichkeit - Straussendung in Absorberrumen This Technical Report was approved by CENELEC on 2009-12-17. CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Icela
8、nd, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. PD CLC/TR 50485:2010CLC/TR 50485:2010 2 Foreword This Technical Report was prepared by the Technical Committee CENELEC
9、TC 210, Electromagnetic Compatibility (EMC). This document supersedes R210-010:2002. In order not to loose the information provided in R210-010:2002, CENELEC TC 210 decided to transfer the content of that document unchanged into a Technical Report. It should be noted that CISPR incorporated a major
10、part of the document R210-010:2002 into the CISPR 16 series and the references to standards were not updated. The document still provides a comprehensive overview and describes some fundamental items of interest for the appropriate use of fully anechoic chambers. The main reason for keeping the docu
11、ment in the public domain in this new form is that it contains background information that has not been included in EN 55016-1-4. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and CENELEC shall not be held responsible for id
12、entifying any or all such patent rights. PD CLC/TR 50485:2010 3 CLC/TR 50485:2010 Contents 1 Scope 5 2 References .5 3 Definitions and abbreviations 6 3.1 Definitions .6 3.2 Abbreviations 7 4 Test and measurement equipment 7 4.1 Fully Anechoic Rooms (FARs) 7 4.2 Antenna .7 5 Anechoic room performanc
13、e .8 5.1 Theoretical normalised site attenuation 8 5.2 Room validation procedure 10 5.3 Anechoic room requirements . 13 6 Emission measurement . 13 6.1 Test set up . 13 6.2 EUT position . 15 6.3 Cable layout and termination . 16 7 Test procedure . 17 8 Test plan 17 9 Test report . 18 Annex A (inform
14、ative) Determining the Site Reference . 19 Annex B (informative) Limit values 21 Annex C (informative) Comparison of measurement uncertainties for 3 m OATS and 3 m FAR . 27 C.1 Introduction 27 C.2 Uncertainty budgets for 3 m OATS and 3 m FAR 28 C.3 Comments on uncertainty budgets 30 Annex D (informa
15、tive) Derivation of free space NSA formula . 32 D.1 Theoretical free space Normalised Site Attenuation 32 D.2 NSA formula for near-field separations 35 Annex E (informative) Corrections of field strength for test distance 36 E.1 Introduction 36 E.2 Field strength correction factor for LPDAs . 37 Ann
16、ex F (informative) NSA measurements with biconical antennas . 38 F.1 Background 38 F.2 ANSI method 39 F.3 Conclusion . 39 Annex G (informative) Measurement of Balun imbalance . 40 Annex H (informative) FAR project . 41 H.1 Description of the FAR project . 41 H.2 Rationale of the FAR project 41 Bibli
17、ography . 43 PD CLC/TR 50485:2010CLC/TR 50485:2010 4 Figures Figure 1 Theoretical NSA 9 Figure 2 Measurement points in room validation procedure 11 Figure 3 Typical test set-up in FAR, where a, b, c and e depend on the room performance 14 Figure 4 Typical test set-up for table top equipment within t
18、he test volume of a FAR . 15 Figure 5 Typical test set-up for floor standing equipment within the test volume of a FAR . 16 Figure A.1 Free space site reference measurement set up . 20 Figure B.1 Differences in emission measurement results between OATS and FAR . 22 Figure B.2 Geometrical optics mode
19、l for OATS measurements 23 Figure B.3 Field attenuation between two half-wave dipoles above ground plane with fixed transmit antenna height and variable receive antenna height . 23 Figure B.4 Equivalent circuit diagram of a typical Equipment Under Test (EUT) 24 Figure B.5 Differences in the received
20、 field strength of an electrically short straight wire on an ideal OATS (1 m 4 m scan of the receive antenna), and in a FAR (EOATS EFAR) 25 Figure B.6 Differences in the received field strength of an electrically short straight wire on an ideal OATS (1 m 4 m scan of the receive antenna), and in a FA
21、R (EOATS EFAR) 26 Figure F.1 NSA values for free space, calculated for a small and a large biconical antenna separated by 3 m 38 Tables Table 1 Frequency ranges and step sizes . 11 Table 2 Relation between maximum diameter of EUT and test distance 13 Table B.1 Preferred limits . 21 Table C.1 Uncerta
22、inty budget for emission measurements on 3 m open area test site 28 Table C.2 Uncertainty budget for emission measurements in 3 m FAR 29 PD CLC/TR 50485:2010 5 CLC/TR 50485:2010 1 Scope This Technical Report applies to emission measurements of radiated electromagnetic fields in Fully Anechoic Rooms
23、(FAR) in the frequency range from 30 MHz to 18 GHz. This Technical Report covers the frequency range from 30 MHz 1 000 MHz. The frequency range above 1 GHz is under consideration, due to the absence of practical experience. This Technical Report describes the validation procedure for the Fully Anech
24、oic Room for radiated emission tests and the procedures to carry out the tests (e.g. test set up, EUT position, cable layout and termination, test procedures). Recommendations for the relation between FAR emission limits and common Open Area Test Site (OATS) emission limits given in standards such a
25、s EN 55011 and EN 55022 are given in Annex B. This FAR emission method may be chosen by product committees as an alternative method to emission measurement on an Open Area Test Site (OATS) as described in CISPR 16 series. In such cases, the product committee should also define the appropriate limits
26、. Typical measurement uncertainty values for FARs and OATS are given in Annex C. 2 References The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced
27、document (including any amendments) applies. EN 50147-1, Anechoic chambers Part 1: Shield attenuation measurement EN 55011, Industrial, scientific and medical (ISM) radio-frequency equipment Electromagnetic disturbance characteristics Limits and methods of measurement (CISPR 11, mod.) EN 55022:1998
28、1), Information technology equipment Radio disturbance characteristics Limits and methods of measurement (CISPR 22:1997, mod.) CISPR 16-1:1999 2), Specification for radio disturbance and immunity measuring apparatus and methods Part 1: Radio disturbance and immunity measuring apparatus CISPR 16-2 3)
29、, Specification for radio disturbance and immunity measuring apparatus and methods Part 2: Methods of measurement of disturbance and immunity CISPR 16-3:2000 4), Specification for radio disturbance and immunity measuring apparatus and methods Part 3: Reports and recommendations of CISPR CISPR 16-4 s
30、eries, Specification for radio disturbance and immunity measuring apparatus and methods Part 4: Uncertainties, statistics and limit modelling IEC 60050-161, International Electrotechnical Vocabulary (IEV) Chapter 161: Electromagnetic compatibility 1)Superseded by EN 55022:2006, Information technolog
31、y equipment Radio disturbance characteristics Limits and methods of measurement (CISPR 22:2005, mod.). 2)Superseded by CISPR 16-1 series, harmonized as EN 55016-1 series, Specification for radio disturbance and immunity measuring apparatus and methods Part 1: Radio disturbance and immunity measuring
32、 apparatus. 3)Superseded by CISPR 16-2 series, harmonized as EN 55016-2 series, Specification for radio disturbance and immunity measuring apparatus and methods Part 2: Methods of measurement of disturbance and immunity. 4)Superseded by CISPR 16-3:2003, Specification for radio disturbance and immuni
33、ty measuring apparatus and methods Part 3: CISPR technical reports. PD CLC/TR 50485:2010CLC/TR 50485:2010 6 3 Definitions and abbreviations 3.1 Definitions For the purposes of this document, the terms and definitions given in IEC 60050-161 and the following apply. 3.1.1 Fully Anechoic Room (FAR) shi
34、elded enclosure whose internal surfaces are lined with radio frequency absorbing material (i.e. RAM), that absorbs electromagnetic energy in the frequency range of interest NOTE The fully Absorber-Lined Room is intended to simulate free space environment. 3.1.2 Equipment Under Test (EUT) test sample
35、 including connected cables NOTE The EUT may consist of one or several pieces of equipment. 3.1.3 test volume region of the room that meets the NSA requirements of this Technical Report and which contains the EUT as fully set up 3.1.4 free space antenna factor (AFFS) antenna factor of an antenna whi
36、ch is not affected by mutual coupling to conducting bodies in the environment of the antenna NOTE It is also the antenna factor measured when the antenna under test is illuminated by a plane wave, which implies that the source antenna is in the far-field of the antenna under test. Antenna factor is
37、defined as the ratio of the magnitude of the E-field in which the antenna is immersed to the voltage at the antenna output of a given transmission line impedance, usually 50 . 3.1.5 antenna reference point physical position on the antenna from which the separation distance to the defined reference p
38、lane on the EUT is measured NOTE For dipole and biconical antennas this will be the centre of the antenna in line with the central antenna elements. For an LPDA antenna and a hybrid antenna, the reference point is the mark on the antenna provided by the manufacturer for this purpose. The reference p
39、oint is approximately at the mid-way point between the array elements that are active at the top and bottom frequencies at which the measurements are being made. Hybrid antenna is here defined as a combination of a biconical and LPDA antenna which has a frequency range including 30 MHz to 1 GHz. 3.1
40、.6 Normalised Site Attenuation (NSA) site attenuation obtained from the ratio of the source voltage connected to a transmitting antenna and the received voltage as measured on the receiving antenna terminals NOTE Normalised site attenuation is site attenuation in decibels minus the antenna factors o
41、f the transmit and receive antenna factors. NSA was first introduced for evaluation of open area test sites with ground planes and was measured by height scanning the receive antenna. In this Technical Report, NSA is measured in a quasi-free space environment, and because there is no deliberate grou
42、nd plane, height scanning is not required. 3.1.7 test distance (dt) distance measured from the reference point of the antenna to the front of the boundary of the EUT PD CLC/TR 50485:2010 7 CLC/TR 50485:2010 3.2 Abbreviations For the purposes of this document, the following abbreviations apply. EUT E
43、quipment Under Test FAR Fully Anechoic RoomNSA Normalised Site Attenuation AFFSAntenna Factor (free space) LPDA Log-Periodic Dipole Array OATS Open Area Test Site RS Reference Site SA Site Attenuation SARmeasurement of SA made on RS NEC Numerical Electromagnetic Code4 Test and measurement equipment
44、Equipment in accordance with CISPR 16 series shall be used. 4.1 Fully Anechoic Rooms (FARs) A Fully Anechoic Room is required for the emission testing in which the radiated electromagnetic waves propagate as in free space and only the direct ray from the transmitting antenna reaches the receiving an
45、tenna. All indirect and reflected waves shall be minimised with the use of proper absorbing material on all walls, the ceiling and the floor of the FAR. The screening of the FAR shall have an adequate attenuation level to avoid outside electromagnetic radiation entering the room and influencing the
46、measurement results. The shield attenuation is measured in accordance with EN 50147-1. Shielding recommendations are given in CLC/TR 50484. 4.2 Antenna Linear polarised antennas shall be used to measure the emitted electromagnetic field of the EUT. Biconical or log-periodic antennas and hybrid anten
47、nas are typical antennas used. The free space antenna factor shall be used. CISPR 16-3:2000, 4.7 gives parameters of broadband antennas. However no length limitation on LPDA or hybrid antennas is given. CISPR 16-1:1999, 5.5.4 and 5.5.5 give information on antennas. CISPR 16-1:1999, 5.5.5.2 b) states
48、 “it is essential that the variation of the effective distance of the antenna from the source and its gain with frequency be taken into account”. Antennas over 1,5 m in length could increase the uncertainties of emission testing using a separation of 3 m between the reference point of the antenna an
49、d the front of the EUT. PD CLC/TR 50485:2010CLC/TR 50485:2010 8 5 Anechoic room performance 5.1 Theoretical normalised site attenuation The Site Attenuation (SA) is the loss measured between the connectors of two antennas on a particular site. For a free space environment the SA (in dB) can be defined by Equation (1) (see Annex D): () ()dBlog2011125log20TRm1042O10AFAFfdddZSA +=(1)where AFRis the antenna facto
