CLC/TR 50485:2010

SLOVENSKI STANDARD
01-december-2011
1DGRPHãþD
SIST R210-010:2003
Elektromagnetna združljivost - Meritve oddajanja v popolnoma neodbojnih sobah
Electromagnetic compatibility - Emission measurements in fully anechoic chambers
Elektromagnetische Verträglichkeit - Störaussendung in Absorberräumen
Compatibilité électromagnétique - Emission en chambres anéchoïques entiers
Ta slovenski standard je istoveten z: CLC/TR 50485:2010
ICS:
33.100.10 Emisija Emission
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

TECHNICAL REPORT
CLC/TR 50485
RAPPORT TECHNIQUE
March 2010
TECHNISCHER BERICHT
ICS 33.100.10 Supersedes R210-010:2002

English version
Electromagnetic compatibility -
Emission measurements in fully anechoic chambers

Compatibilité électromagnétique -  Elektromagnetische Verträglichkeit -
Emission en chambres Störaussendung in Absorberräumen
anéchoïques entiers
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, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania,
Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: Avenue Marnix 17, B - 1000 Brussels

© 2010 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. CLC/TR 50485:2010 E
Foreword
This Technical Report was prepared by the Technical Committee CENELEC 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 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 document 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 identifying any or all such patent
rights.
– 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 performance .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 (informative) 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 (informative) 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
Annex 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
Bibliography . 43

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 the 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 model 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 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 (E – E ) . 25
OATS FAR
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 FAR (E – E ) . 26
OATS FAR
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 – Uncertainty 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

– 5 – CLC/TR 50485:2010
1 Scope
This Technical Report applies to emission measurements of radiated electromagnetic fields in Fully
Anechoic Rooms (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 Anechoic 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 as 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. 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
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.)
1)
EN 55022:1998 , Information technology equipment – Radio disturbance characteristics – Limits and
methods of measurement (CISPR 22:1997, mod.)
2)
CISPR 16-1:1999 , Specification for radio disturbance and immunity measuring apparatus and methods
– Part 1: Radio disturbance and immunity measuring apparatus
3)
CISPR 16-2 , Specification for radio disturbance and immunity measuring apparatus and methods –
Part 2: Methods of measurement of disturbance and immunity
4)
CISPR 16-3:2000 , Specification for radio disturbance and immunity measuring apparatus and methods
– Part 3: Reports and recommendations of CISPR
CISPR 16-4 series, 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 technology 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 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 immunity measuring apparatus and methods – Part 3:
CISPR technical reports.
3 Definitions and abbreviations
3.1
...