EN 61000-4-21:2003

SLOVENSKI SIST EN 61000-4-21:2005

STANDARD
julij 2005
Elektromagnetna združljivost (EMC) – 4-21. del: Preskusne in merilne tehnike –
Preskusne metode za odbojne sobe
Electromagnetic compatibility (EMC) – Part 4-21: Testing and measurement
techniques – Reverberation chamber test methods
ICS 33.100.01 Referenčna številka
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

EUROPEAN STANDARD EN 61000-4-21
NORME EUROPÉENNE
EUROPÄISCHE NORM October 2003

ICS 33.100.10; 33.100.20
English version
Electromagnetic compatibility (EMC)
Part 4-21: Testing and measurement techniques –
Reverberation chamber test methods
(IEC 61000-4-21:2003)
Compatibilité électromagnétique (CEM) Elektromagnetische Verträglichkeit (EMV)
Partie 4-21: Techniques d'essai Teil 4-21: Prüf- und Messverfahren -
et de mesure – Verfahren für die Prüfung
Méthodes d'essai en chambre in der Modenverwirbelungskammer
réverbérante (IEC 61000-4-21:2003)
(CEI 61000-4-21:2003)
This European Standard was approved by CENELEC on 2003-10-01. 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 without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and
notified to the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech Republic,
Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and United Kingdom.

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

Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2003 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 61000-4-21:2003 E
Foreword
The text of document CISPR/A/455/FDIS, future edition 1 of IEC 61000-4-21, prepared by
CISPR SC A, Radio-interference measurements and statistical methods, in cooperation with SC 77B,
High-frequency phenomena, of IEC TC 77, Electromagnetic compatibility, was submitted to the
IEC-CENELEC parallel vote and was approved by CENELEC as EN 61000-4-21 on 2003-10-01.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2004-07-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2006-10-01

Annexes designated "normative" are part of the body of the standard.
Annexes designated "informative" are given for information only.
In this standard, annexes B, C, D, E and ZA are normative and annexes A, F, G, H, I, J are
informative.
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 61000-4-21:2003 was approved by CENELEC as a
European Standard without any modification.
__________
- 3 - EN 61000-4-21:2003
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
This European Standard incorporates by dated or undated reference, provisions from other
publications. These normative references are cited at the appropriate places in the text and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions of any
of these publications apply to this European Standard only when incorporated in it by amendment or
revision. For undated references the latest edition of the publication referred to applies (including
amendments).
NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
Publication Year Title EN/HD Year
IEC 60050-161 1990 International Electrotechnical - -
Vocabulary (IEV)
Chapter 161: Electromagnetic
compatibility
1) 2)
IEC 60068-1 - Environmental testing EN 60068-1 1994
Part 1: General and guidance
1) 2)
IEC 61000-4-3 - Electromagnetic compatibility (EMC) EN 61000-4-3 2002
Part 4-3: Testing and measurement
techniques - Radiated, radio-frequency,
electromagnetic field immunity test

1)
IEC 61000-4-6 - Part 4-6: Testing and measurement - -
techniques - Immunity to conducted
disturbances, induced by radio-
frequency fields
1)
CISPR 16-1 - Specification for radio disturbance and - -
immunity measuring apparatus and
methods
Part 1: Radio disturbance and immunity
measuring apparatus
1)
CISPR 16-2 - Part 2: Methods of measurement of - -
disturbances and immunity
1)
Undated reference.
2)
Valid edition at date of issue.

NORME CEI
INTERNATIONALE
IEC
61000-4-21
INTERNATIONAL
Première édition
STANDARD
First edition
2003-08
PUBLICATION FONDAMENTALE EN CEM
BASIC EMC PUBLICATION
Compatibilité électromagnétique (CEM) –
Partie 4-21:
Techniques d'essai et de mesure –
Méthodes d'essai en chambre réverbérante
Electromagnetic compatibility (EMC) –
Part 4-21:
Testing and measurement techniques –
Reverberation chamber test methods
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61000-4-21 © IEC:2003 – 3 –
CONTENTS
FOREWORD . 7
INTRODUCTION .11
1 Scope .13
2 Normative references.13
3 Definitions and acronyms .15
4 General.21
5 Test environments and limitations .23
6 Applications .23
7 Test equipment .25
8 Chamber calibration .27
9 Testing .29
10 Test results, test report and test conditions .29
Annex A (informative) Reverberation chamber overview.31
Annex B (normative) Chamber calibration for mode-tuning.79
Annex C (normative) Chamber calibration for mode-stirring.99
Annex D (normative) Radiated immunity tests .109
Annex E (normative) Radiated emissions measurements .119
Annex F (informative) Shielding effectiveness measurements of cable assemblies,
cables, connectors, waveguides and passive microwave components .129
Annex G (informative) Shielding effectiveness measurements of gaskets and materials .137
Annex H (informative) Shielding effectiveness measurements of enclosures .161
Annex I (informative) Antenna efficiency measurements .177
Annex J (informative) Direct evaluation of reverberation performance using field
anisotropy and field inhomogeneity coefficients.181
Figure A.1 – Typical field uniformity for 200 tuner steps .57
Figure A.2 – Theoretical modal structure for a 10,8 m × 5,2 m × 3,9 m chamber.57
Figure A.3 – Theoretical modal structure with quality factor bandwidth superimposed on
60th mode .59
Figure A.4 – Theoretical modal structure with greater quality factor bandwidth (lower Q)
th
superimposed on 60 mode.59
Figure A.5 – Typical reverberation chamber facility .61
Figure A.6 – Theoretical sampling requirements for 95 % confidence [see equation
(A.3) on calculating mode density] .63
Figure A.7 – Theoretical sampling requirements for reduced confidence .65
Figure A.8 – Normalized PDF of an electric field component at a fixed location for a
measurement with a single sample .65
Figure A.9 – Normalized PDF of the mean of an electric field component at a fixed
location for a measurement with N samples .67

61000-4-21 © IEC:2003 – 5 –
Figure A.10 – Normalized PDF of the maximum of an electric field component at a fixed
location for a measurement with N samples .67
Figure A.11 – Chamber working volume.69
Figure A.12 – Typical probe data .71
Figure A.13 – Mean-normalized data for x component of 8 probes .73
Figure A.14 – Standard deviation of data for E-field components of 8 probes .73
Figure A.15 – Distribution of absorbers for loading effects test.75
Figure A.16 – Magnitude of loading from loading effects test.75
Figure A.17 – Standard deviation data for electric field components of eight probes in
the loaded chamber.77
Figure B.1 – Probe locations for chamber calibration .97
Figure C.1 – Received power (dBm) as a function of tuner rotation (s) at 500 MHz .107
Figure C.2 – Received power (dBm) as a function of tuner rotation (s) at 1 000 MHz .107
Figure D.1 – Example of suitable test facility.117
Figure E.1 – Example of suitable test facility.127
Figure F.1 – Typical test set-up .135
Figure G.1 – Typical test set-up .155
Figure G.2 – Typical test fixture installation for gasket and/or material testing .157
Figure G.3 – Test fixture configured for calibration.159
Figure H.1 – Typical test enclosure installation for floor mounted enclosure testing .173
Figure H.2 – Typical test enclosure installation for bench mounted enclosure testing.175
Figure J.1 – Theoretical and typical measured distributions for field anisotropy
coefficients in a well-stirred chamber .195
Figure J.2 – Theoretical and typical measured distributions for field anisotropy
coefficients in a poorly stirred chamber.197
Figure J.3 – Typical measured values for field anisotropy coefficients as a function of N
in a well-stirred chamber .199
Figure J.4 – Typical measured values for field anisotropy coefficients as a function of N
in a poorly stirred chamber .201
Table A.1 – Sampling requirements .45
Table B.1 – Sampling requirements .95
Table B.2 – Field uniformity tolerance requirements.95
Table J.1 – Typical values for total field anisotropy coefficients for ‘medium’ and ‘good’
reverberation quality.191

61000-4-21 © IEC:2003 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTROMAGNETIC COMPATIBILITY (EMC) –
Part 4-21: Testing and measurement techniques –
Reverberation chamber test methods
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, and Guides (hereafter referred to as “IEC Publication(s)”). Their preparation is entrusted to
technical committees; any IEC National Committee interested in the subject dealt with may participate in this
preparatory work. International, governmental and non-governmental organizations liaising with the IEC also
participate in this preparation. IEC collaborates closely with the International Organization for Standardization
(ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61000-4-21 has been prepared by CISPR subcommittee A: Radio
interference measurements and statistical methods, in cooperation with subcommittee 77B:
High-frequency phenomena, of IEC technical committee 77: Electromagnetic compatibility.
It forms Part 4-21 of IEC 61000. It has the status of a basic EMC publication in accordance
with IEC Guide 107.
The text of this standard is based on the following documents:
FDIS Report on voting
CISPR/A/455/FDIS CISPR/A/469/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.

61000-4-21 © IEC:2003 – 9 –
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication will remain unchanged until
2005. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
61000-4-21 © IEC:2003 – 11 –
INTRODUCTION
IEC 61000 is published in separate parts according to the following structure:
Part 1: General
General considerations (introduction, fundamental principles)
Definitions, terminology
Part 2: Environment
Description of the environment
Classification of the environment
Compatibility levels
Part 3: Limits
Emission limits
Immunity limits (in so far as they do not fall under the responsibility of the product
committees)
Part 4: Testing and measurement techniques
Measurement techniques
Testing techniques
Part 5: Installation and mitigation guidelines
Installation guidelines
Mitigation methods and devices
Part 6: Generic standards
Part 9: Miscellaneous
Each part is further subdivided into several parts, published either as international standards or
as technical specifications or technical reports, some of which have already been published as
sections. Others will be published with the part number followed by a dash and a second
number identifying the subdivision (example : 61000-6-1).

61000-4-21 © IEC:2003 – 13 –
ELECTROMAGNETIC COMPATIBILITY (EMC) –
Part 4-21:Testing and measurement techniques –
Reverberation chamber test methods
1 Scope
This part of IEC 61000 considers immunity and wanted and unwanted emissions tests for
electric and/or electronic equipment and screening effectiveness tests. Only radiated
phenomena are considered. It establishes the required test procedures for using reverberation
chambers for performing radiated immunity, radiated emissions and screening effectiveness
testing.
The object of this part is to establish a common reference for using reverberation chambers to
evaluate the performance of electric and electronic equipment when subjected to radio-
frequency electromagnetic fields and for determining the levels of radio-frequency radiation
emitted from electric and electronic equipment.
NOTE Test methods are defined in this part for measuring the effect of electromagnetic radiation on equipment
and the electromagnetic emissions from equipment concerned. The simulation and measurement of electro-
magnetic radiation is not adequately exact for quantitative determination of effects. The test methods defined are
structured for the primary objective of establishing adequate repeatability of results at various test facilities for
qualitative analysis of effects.
This part of IEC 61000 does not intend to specify the tests to be applied to particular apparatus
or system(s). Its main aim is to give a general basic reference to all concerned product
committees of the IEC. The product committees are to select emission limits and test methods
in consultation with CISPR. The product committees remain responsible for the appropriate
choice of the immunity tests and the immunity test limits to be applied to their equipment. This
part of IEC 61000 describes other test methods than IEC 61000-4-3 and CISPR 16-2. The
other methods may be used in consultation with CISPR and TC 77, if so specified by product
committees.
2 Normative 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.
IEC 60050(161):1990, International Electrotechnical Vocabulary (IEV) – Chapter 161: Electro-
magnetic compatibility
IEC 60068-1, Environmental testing – Part 1: General and guidance
IEC 61000-4-3, Electromagnetic compatibility (EMC) – Part 4-3: Testing and measurement
techniques – Radiated, radio-frequency, electromagnetic field immunity test
IEC 61000-4-6, Electromagnetic compatibility (EMC) – Part 4-6: Testing and measurement
techniques – Immunity to conducted disturbances, induced by radio-frequency fields

61000-4-21 © IEC:2003 – 15 –
CISPR 16-1, Specification for radio disturbance and immunity measuring apparatus and
methods – Part 1: Radio disturbance and immunity measuring apparatus
CISPR 16-2, Specification for radio disturbance and immunity measuring apparatus and
methods – Part 2: Methods of measurement of disturbances and immunity
3 Definitions and acronyms
3.1 Definitions
For the purposes of this part of IEC 61000-4, the following definitions, together with those in
IEC 60050(161) apply.
3.1.1
antenna
that part of a radio transmitting or receiving system which is designed to provide the required
coupling between a transmitter or a receiver and the medium in which the radio wave
propagates
[IEV 712-01-01]
NOTE For the purpose of this procedure antennas are assumed to have an efficiency of 75 % or greater.
3.1.2
electromagnetic (EM) wave
variations of the conditions of a material medium or vacuum, characterized by a time-varying
electromagnetic field, and moving with a velocity defined at each point and in each direction by
the properties of the medium
NOTE An electromagnetic wave is produced by variations of electric charges or of electric currents.
[IEV 121-11-63]
3.1.3
far field region
that region of the electromagnetic field of an antenna wherein the predominant components of
the field are those which represent a propagation of energy and wherein the angular field
distribution is essentially independent of the distance from the antenna
NOTE 1 In the far field region, all the components of the electromagnetic field decrease in inverse proportion to the
distance from the antenna.
NOTE 2 For a broadside antenna having a maximum overall dimension, D, which is large compared to the wave-
length, λ, the far field region is commonly taken to exist at distances greater than 2D λ from the antenna in the
direction of maximum radiation.
[IEV 712-02-02]
3.1.4
field strength
measurement, made in the far field, of either the electric or the magnetic component of the
field and expressed as V/m or A/m; any one of these measurements may be converted into the
others
NOTE For measurements made in the near field, the term "electric field strength" or "magnetic field strength" is
used according to whether the resultant electric or magnetic field, respectively, is measured. In this field region, the
relationship between the electric and magnetic field strength and distance is complex and difficult to predict, being
dependent on the specific configuration involved. Inasmuch as it is not generally feasible to determine the time and
space phase relationship of the various components of the complex field, the power flux density of the field is
similarly indeterminate.
61000-4-21 © IEC:2003 – 17 –
The IEEE Std 100 definition is as follows:
field strength
(electromagnetic wave) A general term that usually means the magnitude of the electric field vector, commonly
expressed in V/m, but that may also mean the magnitude of the magnetic field vector, commonly expressed in
A/m.
NOTE At frequencies above about 100 MHz, and particularly above 1 000 MHz, field strength in the far zone is
sometimes identified with power flux density P. For a linearly polarized wave in free space P = E()µ /İ ,
v v
where
E is the electric field strength, and
µ and ε are the magnetic and electric constants of free space, respectively.
v v
When P is expressed in W/m and E in V/m, the denominator is often rounded off to 120π. See also: electric
field strength; magnetic field strength; measurement system.
3.1.5
polarization
Ÿ
P
at a given point within a domain of quasi-infinitesimal volume V, vector quantity equal to the
Ÿ
vector electric dipole moment p of the substance contained within the domain divided by the
volume V
Ÿ
Ÿ
p
P = (1)
V
Ÿ
NOTE 1 The electric polarization, P , satisfies the relation
Ÿ
D =İ E + P (2)
where
D is the electric flux density,
E the electric field strength, and
ε the dielectric constant.
[IEV 121-11-37, modified]
NOTE 2 Magnetic polarization (symbols B , J) is the vector quantity equal to the product of the magnetization, M,
i
and magnetic constant, µ :
J = µ M (3)
[IEV 121-11-54]
3.1.6
reverberation chamber
shielded enclosure that is generally equipped with mechanical tuners/stirrers which change
(stir) the boundary conditions within the enclosure and, thus, alter the structure of the
electromagnetic fields within the enclosure
NOTE Testing in a reverberation chamber can be described as a stochastic process in which the mechanical
tuners/stirrers “stir” the “modes” inside the enclosure. The chambers are also called stirred-mode, mode-stirred or
mode-tuned chambers.
61000-4-21 © IEC:2003 – 19 –
3.1.7
reverberation chamber quality factor
Q
the chamber quality factor or “Q” is a measure of how well the chamber stores energy (see
1)
A.6[2] ). For a given chamber, Q varies as a function of frequency and can be calculated using
the following:
16π V P
AveRec
Q = (4)
P
Ș Ș λ
input
Tx Rx
where
V is the chamber volume (m ),
λ is the wavelength (m),
(

) is the ratio of the average received power to the input power over one
AveRec input
complete tuner/stirrer sequence, and
η and η are the antenna efficiency factors for the Transmit (Tx) and Receive (Rx)
Tx Rx
antennas, respectively. (If manufacturer’s data is not available then the
efficiency can be assumed to be 0,75 for log periodic antennas and 0,9 for
horn antennas.)
3.1.8
reverberation chamber Q-bandwidth (BW )
Q
the BW is a measure of the frequency bandwidth over which the modes in a reverberation
Q
chamber are correlated (see Clause A.2). The BW of a reverberation chamber can be
Q
calculated using the following:
BW = f/Q (5)
Q
where
f is the frequency, and
Q is the quality factor defined in 3.1.7.
3.1.9
malfunction
termination of the ability of an equipment to carry out intended functions or the execution of
unintended functions by the equipment
3.1.10
radiated emissions
any wanted or unwanted emission from an electrical device
3.1.11
tuner/stirrer
mechanical device constructed from electrically conductive material which alters the
electromagnetic boundary conditions within reverberation chambers
NOTE In general, a reverberation chamber is a shielded enclosure with the smallest dimension being large with
respect to the wavelength at the lowest useable frequency. The chamber is normally equipped with a mechanical
tuning/stirring device whose dimensions are a significant fraction of the chamber dimensions and of the wavelength
at the lowest useable frequency. When the chamber is excited with RF energy, the boundary conditions of the
resulting multi-mode electromagnetic environment can be “altered” by the mechanical tuner/stirrer. The resulting
environment is statistically uniform and statistically isotropic (i.e., the energy having arrived from all aspect angles
and at all polarizations) when averaged over a sufficient number of positions of the mechanical tuner/stirrer.
———————
1)
Numbers in brackets refer to the reference documents in the respective annexes.

61000-4-21 © IEC:2003 – 21 –
3.2 Acronyms
ACF Antenna Calibration Factor
CCF Chamber Calibration Factor
CDF Cumulative Distribution Function
CISPR Comité International Spécial des Perturbations Radioélectriques
CLF Chamber Loading Factor
CW Continuous Wave
EM Electromagnetic
EMC Electromagnetic Compatibility
EMI Electromagnetic Interference
EUT Equipment Under Test
IEC International Electrotechnical Commission
IEEE Institute of Electrical and Electronics Engineers
IEV International Electrotechnical Vocabulary
IF Image Frequency
IL Insertion Loss
ISO International Standardization Organization
JTF Joint Task Force
LUF Lowest Usable Frequency
NIST National Institute of Standards and Technology
OATS Open Area Test Site
PDF Probability Density Function
RE Radiated Emissions
RF Radio Frequency
RMS Root Mean Square
RSS Root Sum of the Squares
Rx Receive (antenna)
SE Shielding Effectiveness
SW Square Wave modulation
TFCF Test Fixture Calibration Factor
Tx Transmit (antenna)
4 General
Most electronic equipment is, in some manner, affected by electromagnetic radiation. This
radiation is frequently generated by such sources as the small hand-held radio transceivers that
are used by operating, maintenance and security personnel, fixed-station radio and television
transmitters, vehicle radio transmitters and various industrial electromagnetic sources.
High-level electromagnetic fields are easily and safely generated using reverberation
chambers. The high quality factor or “Q” of most chambers allows fairly high field strengths to
be generated with moderate input powers, and the absence of absorber makes generation of
high field levels safer as the risk of igniting absorbers is eliminated.
In addition to electromagnetic energy deliberately generated, there are also radiated
disturbances caused by devices such as welders, thyristors, fluorescent lights, switches
operating inductive loads, etc. For the most part, this disturbance manifests itself as conducted
electrical disturbance and, as such, is dealt with in other parts of IEC 61000-4. However, this
standard does deal with how to measure radiated emissions from such devices. Methods
employed to prevent effects from electromagnetic fields will normally also reduce the effects
from these sources.
The electromagnetic environment is determined by the strength of the electromagnetic field
(electric field strength in V/m and magnetic field in A/m). The field strength is not easily
measured without sophisticated instrumentation nor is it easily calculated by classical
equations and formulae because of the effect of surrounding structures or the proximity of
other equipment that will distort and/or reflect the electromagnetic waves.

61000-4-21 © IEC:2003 – 23 –
5 Test environments and limitations
The reverberation chamber method is suitable for performing testing from extremely low to
extremely high field levels. Due to the high level of separation from the ambient environment,
both emissions and immunity tests can be performed for most commercial requirements
without limitations.
As stated in Annex A, the frequency range of tests is determined by the size and construction
of the chamber and the effectiveness of the mechanical tuner(s). Room-sized reverberation
3 3
chambers (e.g., volumes of between 75 m to 100 m ) are typically operated from 200 MHz to
18 GHz without limitations. Operations below 200 MHz require chambers that are larger than
the typical shielded room. At present, the IEC sets the transition frequency between radiated
and conducted testing at 80 MHz for immunity testing.
NOTE IEC 61000-4-6 also defines test methods for establishing the immunity of electrical and electronic
equipment against conducted electromagnetic energy. It covers frequencies below 80 MHz.
6 Applications
6.1 Radiated immunity
The use of reverberation chambers for performing radiated immunity testing is covered in
Annex D. This Annex covers test set-up, chamber calibration, and test procedures. Injecting a
predetermined level of RF power into the chamber generates the desired field strengths within
the chamber. This predetermined level of RF power is derived from chamber calibration data
described in Annexes B and/or C.
6.2 Radiated emissions
Using reverberation chambers to measure radiated emissions (both intentional and
unintentional) is covered in Annex E. The method described measures the amount of RF power
radiated by the EUT within the measurement bandwidth. As with radiated immunity testing,
chamber calibration data described in Annexes B and/or C is used to determine radiated
emissions levels.
6.3 Screening effectiveness measurements
Three annexes are devoted to conducting screening effectiveness measurements. Screening
effectiveness measurements of cables assemblies, cables, connectors, waveguides and
passive microwave components are described in Annex F. Annex G covers screening
effectiveness of gaskets and materials. The approach outlined in Annex G uses a “nested
chamber” methodology (e.g., a reverberation chamber within a reverberation chamber). This
annex also covers calibration of test fixtures that are usually necessary for conducting
screening measurements on gaskets and materials. Minor differences in test fixture design/
construction can have significant influence on test results. Fixture materials, bolt spacing,
surface finishes, torque settings, etc. must all be controlled in order to get repeatable results.
Due to the large number of variations that would be needed in order to accommodate the many
different gaskets and materials that require evaluation, this annex does not contain detailed
design guidance for test fixtures. Annex H covers screening effectiveness measurements of
enclosures. As in Annex G, the methodology described in Annex H uses the “nested chamber”
approach.
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7 Test equipment
The following types of test equipment are recommended.
– Reverberation chamber: of a size adequate to maintain a multi-mode electromagnetic
environment with respect to the lowest test frequency.
– Mechanical tuner(s)/stirrer(s): with one dimension at least one-quarter wavelength at the
lowest frequency. Each tuner/stirrer should also be as large as possible with respect to
overall chamber size in that one dimension should be at least three-quarters of the smallest
chamber dimension. In addition, each tuner/stirrer should be shaped such that a non-
repetitive field pattern is obtained over one revolution of the tuner/stirrer.
– Field generating antennas (see Annex B): log periodic or any other linearly polarized
antenna system capable of satisfying frequency requirements and avoiding direct
illumination of the test volume.
– Field strength reference antennas (see Annex B): log periodic or any other linearly
polarized antenna system capable of satisfying frequency requirements.
– Isotropic field strength monitoring probe (see Annex B): capable of monitoring the electric
field along all three orthogonal axes. Any probe-head circuitry and opto-electronics shall
have adequate immunity to the field strength to be measured, and a fiber-optic link to the
indicator outside the chamber. An adequately filtered line may also be used.
NOTE 1 Reverberation chambers require a field probe that allows the electric field to be measured individually
along all three orthogonal axes. If a small single-axis antenna is used it must be repositioned to measure each
field component separately.
– Field strength monitoring antenna that is a small (calibrated) dipole antenna (i.e., less than
0,1λ) may be substituted for the probe, provided that the antenna is positioned at three
non-coplanar orientations (mutually perpendicular preferred) for each measurement
location. Care should be taken to maintain the balance of this antenna with respect to its
feed cable.
– EMI filters: care should be taken to ensure that the filters introduce no additional resonance
effects on the connected lines.
– RF signal generator(s) capable of covering the frequency band of interest and which, if
used for immunity testing, can be amplitude modulated by a 1 kHz sinewave to 80 % depth.
–3
They shall have either an automated sweep capability of 1,5 × 10 decade/s or slower or,
in the case of RF synthesizers, be capable of being programmed with frequency-dependent
step-sizes and dwell times. They shall also be capable of being set manually.
NOTE 2 Product committees may select alternative modulation schemes.
The use of low-pass or band-pass filters may be necessary to avoid problems caused by
harmonics to equipment which is intended to receive signals for monitoring purposes.
– Power amplifiers: to amplify signal (unmodulated and modulated) and provide antenna drive
power to the necessary field level. The harmonics and distortion produced by the power
amplifier shall be at a level less than or equal to 15 dB below carrier level.
WARNING – High reflections are present in reverberation chamber tests, amplifier
protection may be required.
– Associated equipment to record the power levels necessary for the required field strength
and to control the generation of that level for testing.
– Associated equipment to record the power levels associated with the required emissions
limits.
Care shall be taken to ensure adequate immunity of the auxiliary equipment.

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8 Chamber calibration
Following the initial construction or after any major modifications, a performance-based field
uniformity calibration technique to demonstrate adequate reverberation chamber performance
is carried out in accordance with Annex B. The procedure is used to determine the lowest
useable frequency (LUF) of the reverberation chamber employed. The chamber field uniformity
calibration described is to be carried out over a test/working volume, which includes the
location of the test bench and equipment under test (EUT) within the reverberation chamber.
The chamber calibration addresses only mode tuned (stepped tuner rotation) operation of the
reverberation chamber: mode-stirred (continuous tuner rotation) operation is addressed
separately in Annex C. The field uniformity measurement should be carried out with all support
equipment (including the test bench) removed from the reverberation chamber. The calibration
is to be carried out at 8 locations for 3 individual axes (x, y, z) at each test location, i.e., 24
measurement points in total (B.1.1). The field within the chamber is considered uniform if the
standard deviation is within 3 dB above 400 MHz, 4 dB at 100 MHz decreasing linearly to 3 dB
at 400 MHz, and within 4 dB below 100 MHz.
The calibration technique requires the use of linear/passive field monitoring antennas during
EUT testing. The antennas are calibrated against a three-axis E-field sensor (calibrated in free
space). The purpose of this aspect of the procedure is to allow continuous monitoring of the
field during the test with an antenna and associated monitoring equipment with a fast response
time. Again, this test is performed with the measurement bench removed and performed at the
same time as the field uniformity test.
In addition, following initial construction or after major modification to the reverberation
chamber a check on the impact on field uniformity of chamber loading is performed (B.1.5) to
determine the maximum acceptable loading of the chamber for future testing.
Prior to the start of each test with the test bench and EUT installed in the chamber, the
following is carried out.
• A “quick check” chamber performance measurement is made with the equipment to be
tested and test bench installed in the chamber (B.2). The purpose of this test is to confirm
that the loading of the chamber is less than that simulated during the initial chamber
calibration.
• Calculations based on the calibration measurements are used to determine the minimum
pulse width (B.3) that can be sustained in a given chamber for pulse modulation testing. If
the chamber time constant is greater than 0,4 times the required pulse width for more than
10 % of the test frequencies, absorbers shall be added or the pulse width increased (not to
exceed 100 µs).
NOTE The chamber calibration detailed in clause B.1 need only be undertaken after initial chamber construction,
and after major modification to the reverberation chamber. The maximum chamber loading verification (A.5.4,
B.1.5) need only be undertaken after initial chamber construction or after major modifications to the reverberation
chamber. Changes to the tuners/stirrers are considered a major modification if the changes result in changes in
tuner efficiency as outlined in clause A.3.

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9 Testing
Test set-up and procedures are dependent upon the type of test being performed. Refer to the
annex that pertains to the type of test being performed to determine the test requirements for a
specific test.
Refer to the annex that pertains to the type of test methodology desired (i.e., mode-tuned or
mode-stirred). For guidance on applicability of mode-tuning versus mode-stirring, refer to
Annexes A and C.
10 Test results, test report and test conditions
Testing shall be performed according to a test plan, which shall be included in the test report.
Test results and reporting requirements are dependent upon the type of test being performed.
Refer to the annex that pertains to the type of test being performed to determine what needs to
be included in the test report.
Unless otherwise stated in the test plan, tests shall be carried out in standard climatic
conditions in accordance with IEC 60068-1.

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Annex A
(informative)
Reverberation chamber overview
A.1 Preliminary remarks
Research on reverberation chambers has been performed for more than 20 years and has
)
provided a significant increase in the understanding of
...