IEC 61000-4-6:2008

IEC 61000-4-6
Edition 3.0 2008-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
BASIC EMC PUBLICATION
PUBLICATION FONDAMENTALE EN CEM
Electromagnetic compatibility (EMC) –
Part 4-6: Testing and measurement techniques – Immunity to conducted
disturbances, induced by radio-frequency fields

Compatibilité électromagnétique (CEM) –
Partie 4-6: Techniques d'essai et de mesure – Immunité aux perturbations
conduites, induites par les champs radioélectriques

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IEC 61000-4-6
Edition 3.0 2008-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
BASIC EMC PUBLICATION
PUBLICATION FONDAMENTALE EN CEM
Electromagnetic compatibility (EMC) –
Part 4-6: Testing and measurement techniques – Immunity to conducted
disturbances, induced by radio-frequency fields

Compatibilité électromagnétique (CEM) –
Partie 4-6: Techniques d'essai et de mesure – Immunité aux perturbations
conduites, induites par les champs radioélectriques

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
XA
CODE PRIX
ICS 33.100.20 ISBN 978-2-88910-376-8
– 2 – 61000-4-6 © IEC:2008
CONTENTS
FOREWORD.5
INTRODUCTION.7
1 Scope and object .8
2 Normative references.8
3 Terms and definitions .8
4 General .10
5 Test levels .10
6 Test equipment.11
6.1 Test generator .11
6.2 Coupling and decoupling devices .12
6.2.1 Coupling/decoupling networks (CDNs) .12
6.2.2 Clamp injection devices .13
6.2.3 Direct injection devices .14
6.2.4 Decoupling networks.14
6.3 Verification of the common mode impedance at the EUT port of coupling and
decoupling devices .14
6.3.1 Insertion loss of the 150 Ω to 50 Ω adapters.15
6.4 Setting of the test generator.15
6.4.1 Setting of the output level at the EUT port of the coupling device.15
7 Test set-up for table-top and floor-standing equipment .16
7.1 Rules for selecting injection methods and test points.16
7.1.1 Injection method .16
7.1.2 Ports to be tested .17
7.2 Procedure for CDN injection application .18
7.3 Procedure for clamp injection when the common-mode impedance
requirements can be met .18
7.4 Procedure for clamp injection when the common-mode impedance

requirements cannot be met .19
7.5 Procedure for direct injection .19
7.6 EUT comprising a single unit .19
7.7 EUT comprising several units.20
8 Test procedure .20
9 Evaluation of the test results .21
10 Test report.21
Annex A (normative) Additional information regarding clamp injection.33
Annex B (informative) Selection criteria for the frequency range of application .38
Annex C (informative) Guide for selecting test levels .40
Annex D (informative) Information on coupling and decoupling networks.41
Annex E (informative) Information for the test generator specification .45
Annex F (informative) Test set-up for large EUTs .46
Annex G (informative) Measurement uncertainty of test instrumentation.49
Bibliography .56

Figure 1 – Rules for selecting the injection method .17

61000-4-6 © IEC:2008 – 3 –
Figure 2 – Immunity test to RF conducted disturbances .23
Figure 3 – Test generator set-up .24
Figure 4 – Open circuit waveforms at the EUT port of a coupling device for test level 1.24
Figure 5 – Principle of coupling and decoupling .27
Figure 6 – Principle of coupling and decoupling according to the clamp injection method .27
Figure 7 – Details of set-ups and components to verify the essential characteristics of
coupling and decoupling devices and the 150 Ω to 50 Ω adapters .29
Figure 8 – Set-up for level setting (see 6.4.1) .30
Figure 9 – Example of test set-up with a single unit EUT.31
Figure 10 – Example of a test set-up with a multi-unit EUT .32
Figure A.1 – Circuit for level setting set-up in a 50 Ω test Jig .34
Figure A.2 – The 50 Ω test jig construction .34
Figure A.3 – Construction details of the EM clamp.35
Figure A.4 – Concept of the EM clamp (electromagnetic clamp).36
Figure A.5 – Coupling factor of the EM clamp .36
Figure A.6 – General principle of a test set-up using injection clamps .37
Figure A.7 – Example of the test unit locations on the ground plane when using
injection clamps (top view) .37
Figure B.1 – Start frequency as function of cable length and equipment size.39
Figure D.1 – Example of a simplified diagram for the circuit of CDN-S1 used with
screened cables (see 6.2.1) .42
Figure D.2 – Example of simplified diagram for the circuit of CDN-M1/-M2/-M3 used

with unscreened supply (mains) lines (see 6.2.1.1) .42
Figure D.3 – Example of a simplified diagram for the circuit of CDN-AF2 used with
unscreened non-balanced lines (see 6.2.1.3).43
Figure D.4 – Example of a simplified diagram for the circuit of a CDN-T2, used with an
unscreened balanced pair (see 6.2.1.2) .43
Figure D.5 – Example of a simplified diagram of the circuit of a CDN-T4 used with
unscreened balanced pairs (see 6.2.1.2) .44
Figure D.6 – Example of a simplified diagram of the circuit of a CDN-T8 used with
unscreened balanced pairs (see 6.2.1.2) .44
Figure F.1 – Example of large EUT test set-up with elevated horizontal ground reference
plane .47
Figure F.2 – Example of large EUT test set-up with vertical ground reference plane.48
Figure G.1 – Example of influences upon the test method using CDN .49
Figure G.2 – Example of influences upon the test method using EM clamp .50
Figure G.3 – Example of influences upon the test method using current clamp.50
Figure G.4 – Example of influences upon the test method using direct injection .50

Table 1 – Test levels .11
Table 2 – Characteristics of the test generator.12
Table 3 – Main parameter of the combination of the coupling and decoupling device.12
Table B.1 – Main parameter of the combination of the coupling and decoupling device

when the frequency range of test is extended above 80 MHz .38
Table E.1 – Required power amplifier output power to obtain a test level of 10 V .45
Table G.1a – CDN calibration process.51

– 4 – 61000-4-6 © IEC:2008
Table G.1b – CDN test process .51
Table G.2a – EM clamp calibration process .53
Table G.2b – EM clamp test process .53
Table G.3a – Current clamp calibration process.54
Table G.3b – Current clamp test process.54
Table G.4a – Direct injection calibration process .55
Table G.4b – Direct injection test process.55

61000-4-6 © IEC:2008 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTROMAGNETIC COMPATIBILITY (EMC) –

Part 4-6: Testing and measurement techniques –
Immunity to conducted disturbances,
induced by radio-frequency fields

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,
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agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
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5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
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6) All users should ensure that they have the latest edition of this publication.
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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 61000-4-6 has been prepared by subcommittee 77B: High-
frequency phenomena, of IEC technical committee 77: Electromagnetic compatibility.
This standard forms part 4-6 of IEC 61000. It has the status of a basic EMC publication in
accordance with IEC Guide 107, Electromagnetic compatibility – Guide to the drafting of
electromagnetic compatibility publications.
This third edition of IEC 61000-4-6 cancels and replaces the second edition published in 2003,
Amendment 1 (2004) and Amendment 2 (2006).This edition constitutes a technical revision.
The document 77B/571/FDIS, circulated to the National Committees as Amendment 3, led to
the publication of the new edition.

– 6 – 61000-4-6 © IEC:2008
The text of this standard is based on the second edition, its Amendment 1, Amendment 2 and
on the following documents:
FDIS Report on voting
77B/571/FDIS 77B/577/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.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of the base publication and its amendments will
remain unchanged until the maintenance result date indicated on the IEC web site under
"http://webstore.iec.ch" in the data related to the specific publication. At this date, the
publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
61000-4-6 © IEC:2008 – 7 –
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).
This part is an international standard which gives immunity requirements and test procedure
related to conducted disturbances induced by radio-frequency fields.

– 8 – 61000-4-6 © IEC:2008
ELECTROMAGNETIC COMPATIBILITY (EMC) –

Part 4-6: Testing and measurement techniques –
Immunity to conducted disturbances,
induced by radio-frequency fields

1 Scope and object
This part of IEC 61000 relates to the conducted immunity requirements of electrical and
electronic equipment to electromagnetic disturbances coming from intended radio-frequency
(RF) transmitters in the frequency range 9 kHz up to 80 MHz. Equipment not having at least
one conducting cable (such as mains supply, signal line or earth connection) which can couple
the equipment to the disturbing RF fields is excluded.
NOTE 1 Test methods are defined in this part for measuring the effect that conducted disturbing signals, induced
by electromagnetic radiation, have on the equipment concerned. The simulation and measurement of these
conducted disturbances are not adequately exact for the quantitative determination of effects. The test methods
defined are structured for the primary objective of establishing adequate repeatability of results at various facilities
for quantitative analysis of effects.
The object of this standard is to establish a common reference for evaluating the functional
immunity of electrical and electronic equipment when subjected to conducted disturbances
induced by radio-frequency fields. The test method documented in this part of IEC 61000
describes a consistent method to assess the immunity of an equipment or system against a
defined phenomenon.
NOTE 2 As described in IEC Guide 107, this standard is a basic EMC publication for use by product committees of
the IEC. As also stated in Guide 107, the IEC product committees are responsible for determining whether this
immunity test standard should be applied or not, and if applied, they are responsible for determining the appropriate
test levels and performance criteria. TC 77 and its sub-committees are prepared to co-operate with product
committees in the evaluation of the value of particular immunity tests for their products.
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, International Electrotechnical Vocabulary (IEV) – Chapter 161: Electro-
magnetic compatibility
3 Terms and definitions
For the purposes of this part of IEC 61000, the terms and definitions given in IEC 60050-161 as
well as the following definitions apply.
3.1
artificial hand
electrical network simulating the impedance of the human body under average operational
conditions between a hand-held electrical appliance and earth
[IEV 161-04-27]
NOTE The construction should be in accordance with CISPR 16-1-2.

61000-4-6 © IEC:2008 – 9 –
3.2
auxiliary equipment
AE
equipment necessary to provide the equipment under test (EUT) with the signals required for
normal operation and equipment to verify the performance of the EUT
3.3
clamp injection
clamp injection is obtained by means of a clamp-on “current” injecting device on the cable:
– current clamp: a transformer, the secondary winding of which consists of the cable into
which the injection is made;
– electromagnetic clamp (EM clamp): injection device with combined capacitive and
inductive coupling
3.4
common-mode impedance
ratio of the common mode voltage and the common-mode current at a certain port
NOTE This common mode impedance can be determined by applying a unity common mode voltage between the
terminal(s) or screen of that port and a reference plane (point). The resulting common mode current is then
measured as the vectorial sum of all currents flowing through these terminal(s) or screen (see also Figures 8a and
8b).
3.5
coupling factor
ratio given by the open-circuit voltage (e.m.f.) obtained at the EUT port of the coupling (and
decoupling) device divided by the open-circuit voltage obtained at the output of the test
generator
3.6
coupling network
electrical circuit for transferring energy from one circuit to another with a defined impedance
NOTE Coupling and decoupling devices can be integrated into one box (coupling and decoupling network (CDN))
or they can be in separate networks.
3.7
coupling/decoupling network
CDN
electrical circuit incorporating the functions of both the coupling and decoupling networks
3.8
decoupling network
electrical circuit for preventing test signals applied to the EUT from affecting other devices,
equipment or systems that are not under test
3.9
test generator
generator (RF generator, modulation source, attenuators, broadband power amplifier and
filters) capable of generating the required test signal (see Figure 3)
3.10
electromotive force
e.m.f.
voltage at the terminals of the ideal voltage source in the representation of an active element
[IEV 131-01-38:1978]
– 10 – 61000-4-6 © IEC:2008
3.11
measurement result
U
mr
voltage reading of the measurement equipment
3.12
voltage standing wave ratio
VSWR
ratio of a maximum to an adjacent minimum voltage magnitude along the line
4 General
The source of disturbance covered by this part of IEC 61000 is basically an electromagnetic
field, coming from intended RF transmitters, that may act on the whole length of cables
connected to installed equipment. The dimensions of the disturbed equipment, mostly a sub-
part of a larger system, are assumed to be small compared with the wavelengths involved. The
in-going and outgoing leads (e.g. mains, communication lines, interface cables) behave as
passive receiving antenna networks because of their length, which can be several wavelengths.
Between those cable networks, the susceptible equipment is exposed to currents flowing
“through" the equipment. Cable systems connected to an equipment are assumed to be in
resonant mode (λ/4, λ/2 open or folded dipoles) and as such are represented by coupling and
decoupling devices having a common-mode impedance of 150 Ω with respect to a ground
reference plane. Where possible the EUT is tested by connecting it between two 150 Ω
common-mode impedance connections: one providing an RF source and the other providing a
return path for the current.
This test method subjects the EUT to a source of disturbance comprising electric and magnetic
fields, simulating those coming from intentional RF transmitters. These disturbing fields (E and
H) are approximated by the electric and magnetic near-fields resulting from the voltages and
currents caused by the test set-up as shown in Figure 2a.
The use of coupling and decoupling devices to apply the disturbing signal to one cable at the
time, while keeping all other cables non-excited, see Figure 2b, can only approximate the real
situation where disturbing sources act on all cables simultaneously, with a range of different
amplitudes and phases.
Coupling and decoupling devices are defined by their characteristics given in 6.2. Any coupling
and decoupling device fulfilling these characteristics can be used. The coupling and decoupling
networks in Annex D are only examples of commercially available networks.
5 Test levels
No tests are required for induced disturbances caused by electromagnetic fields coming from
intentional RF transmitters in the frequency range 9 kHz to 150 kHz.

61000-4-6 © IEC:2008 – 11 –
Table 1 – Test levels
Frequency range 150 kHz – 80 MHz
Voltage level (e.m.f.)
Level
U U
0 0
dB(µV) V
1 120 1
2 130 3
3 140 10
a
X Special
a
X is an open level.
The open-circuit test levels (e.m.f.) of the unmodulated disturbing signal, expressed in r.m.s.,
are given in Table 1. The test levels are set at the EUT port of the coupling devices, see 6.4.1.
For testing of equipment, this signal is 80 % amplitude modulated with a 1 kHz sine wave to
simulate actual threats. The effective amplitude modulation is shown in Figure 4. Guidance for
selecting test levels is given in Annex C.
NOTE 1 IEC 61000-4-3 also defines test methods for establishing the immunity of electrical and electronic
equipment against radiated electromagnetic energy. It covers frequencies above 80 MHz. Product committees may
decide to choose a lower or higher transition frequency than 80 MHz (see Annex B).
NOTE 2 Product committees may select alternative modulation schemes.
6 Test equipment
6.1 Test generator
The test generator includes all equipment and components for supplying the input port of each
coupling device with the disturbing signal at the required signal level at the required point. A
typical arrangement comprises the following items which may be separate or integrated into
one or more test instruments (see 3.9 and Figure 3):
– RF generator(s), G1, capable of covering the frequency band of interest and of being
amplitude modulated by a 1 kHz sine wave with a modulation depth of 80 %. They shall
have manual control (e.g., frequency, amplitude, modulation index) or in the case of RF
synthesizers, they shall be programmable with frequency-dependent step sizes and dwell
times;
– attenuator, T1, (typically 0 dB . 40 dB) of adequate frequency rating to control the
disturbing test source output level. T1 may be included in the RF generator and is optional;
– RF switch, S1, by which the disturbing test signal can be switched on and off when
measuring the immunity of the EUT. S1 may be included in the RF generator and is
optional;
– broadband power amplifier(s), PA, may be necessary to amplify the signal if the output
power of the RF generator is insufficient;
– low-pass filters (LPF), and/or high-pass filters (HPF) may be necessary to avoid
interference caused by (higher order or sub-) harmonics with some types of EUT, for
example RF receivers. When required they shall be inserted in between the broadband
power amplifier, PA, and the attenuator T2;
= 50 Ω), with sufficient power ratings. T2 is provided to
– attenuator, T2, (fixed ≥ 6 dB, Z
o
reduce the mismatch from the power amplifier to the coupling device.
NOTE T2 may be included in a coupling and decoupling network and can be left out if the output impedance of the
broadband power amplifier remains within the specification under any load condition.
Characteristics of the test generator with and without modulation are given in Table 2.

– 12 – 61000-4-6 © IEC:2008
Table 2 – Characteristics of the test generator
Output impedance 50 Ω
Harmonics and distortion any spurious spectral line shall be at
least 15 dB below the carrier level
Amplitude modulation internal or external,
80 % ± 5 % in depth
1 kHz ± 10 % sine wave
Output level sufficiently high to cover test level
(see also Annex E)
6.2 Coupling and decoupling devices
Coupling and decoupling devices shall be used for appropriate coupling of the disturbing signal
(over the entire frequency range, with a defined common-mode impedance at the EUT port) to
the various cables connected to the EUT and for preventing applied test signals from affecting
other devices, equipment and systems that are not under test.
The coupling and decoupling devices can be combined into one box (a coupling/ decoupling
network, CDN) or can consist of several parts. The main coupling and decoupling device
parameter, the common-mode impedance seen at the EUT-port, is specified in Table 3.
The preferred coupling and decoupling devices are the CDNs, for reasons of test reproducibility
and protection of the AE. However, if they are not suitable or available, other injection methods
can be used. Rules for selecting the appropriate injection method are given below and in 7.1.
Table 3 – Main parameter of the combination of the coupling and decoupling device
Frequency band
Parameter 0,15 MHz – 26 MHz 26 MHz – 80 MHz
|Z | 150 Ω ± 20 Ω 150 Ω + 60 Ω – 45 Ω
ce
NOTE 1 Neither the argument of Z nor the decoupling factor between the EUT port and the AE port are specified
ce
separately. These factors are embodied in the requirement that the tolerance of |Z | shall be met with the AE-port
ce
open or short-circuited to the ground reference plane.
NOTE 2 When clamp injection methods are used, without complying with the common-mode impedance
requirements for the auxiliary equipment, the requirements of Z may not be met. However, the injection clamps
ce
can provide acceptable test results when the guidance of 7.4 is followed.
6.2.1 Coupling/decoupling networks (CDNs)
These networks comprise the coupling and decoupling circuits in one box and can be used for
specific unscreened cables e.g. CDN-M1, CDN-M2, CDN-M3, CDN-T2, CDN-T4, CDN-AF-2,
see Annex D. Typical concepts of the coupling and the decoupling networks are given in
Figures 5c and 5d. The networks shall not unduly affect the functional signals. Constraints on
such effects may be specified in the product standards.
6.2.1.1 CDNs for power supply lines
Coupling/decoupling networks are recommended for all power supply connections. However, for
high power (current ≥16 A) and/or complex supply systems (multi-phase or various parallel
supply voltages) other injection methods may be selected.
The disturbing signal shall be coupled to the supply lines, using type CDN-M1 (single wire),
CDN-M2 (two wires) or CDN-M3 (three wires), or equivalent networks (see Annex D). Similar
networks can be defined for a 3-phase mains system. The coupling circuit is given in Figure 5c.

61000-4-6 © IEC:2008 – 13 –
The performance of the CDN shall not be unduly degraded by saturation of the magnetic
material due to current taken by the EUT. Wherever possible, the network construction should
ensure that the magnetising effect of the forward current is cancelled by that due to the return
current.
If in real installations the supply wires are individually routed, separate CDN-M1 coupling and
decoupling networks shall be used and all input ports shall be treated separately.
If the EUT is provided with other earth terminals (e.g. for RF purposes or high leakage
currents), they shall be connected to the ground reference plane:
– through the CDN-M1 when the characteristics or specification of the EUT permit. In this
case, the (power) supply shall be provided through the CDN-M3 network;
– when the characteristics or specification of the EUT do not permit the presence of a CDN-
M1 network in series with the earth terminal for RF or other reasons, the earth terminal
shall be directly connected to the ground reference plane. In this case the CDN-M3 network
shall be replaced by a CDN-M2 network to prevent an RF short circuit by the protective
earth conductor. When the equipment was already supplied via CDN-M1 or CDN-M2
networks, these shall remain in operation.
Warning: The capacitors used within the CDNs bridge live parts. As a result, high leakage
currents may occur and safety connections from the CDN to the ground reference plane are
obligatory (in some cases, these connections may be provided by the construction of the CDN).
6.2.1.2 CDNs for unscreened balanced lines
For coupling and decoupling disturbing signals to an unscreened cable with balanced lines, a
CDN-T2, CDN-T4 or CDN-T8 shall be used as coupling and decoupling network. Figures D.4,
D.5 and D.6 in Annex D show these possibilities:
– CDN-T2 for a cable with 1 symmetrical pair (2 wires);
– CDN-T4 for a cable with 2 symmetrical pairs (4 wires);
– CDN-T8 for a cable with 4 symmetrical pairs (8 wires).
NOTE Other CDN-Tx networks may be used if they are suitable for the intended frequency range and satisfy the
requirements of 6.2. For example, the differential to common mode conversion loss of the CDNs should have a
larger value than the specified conversion ratio of the cable to be installed or equipment connected to the installed
cable. If different conversion ratios are specified for cable and equipment then the smaller value applies. Often,
clamp injection needs to be applied to multi-pair balanced cables because suitable CDNs might not be available.
6.2.1.3 Coupling and decoupling for unscreened non-balanced lines
For coupling and decoupling disturbing signals to an unscreened cable with non-balanced lines,
a coupling and decoupling network as described in Figure D.3 for a single pair may be used.
NOTE If no suitable CDN is available, clamp injection should be used.
6.2.2 Clamp injection devices
With clamp injection devices, the coupling and decoupling functions are separated. Coupling is
provided by the clamp-on device while the common-mode impedance and the decoupling
functions are established at the auxiliary equipment. As such, the auxiliary equipment becomes
part of the coupling and decoupling devices (see Figure 6). Subclause 7.3 gives instructions for
proper application.
When an EM clamp or a current clamp is used without fulfilling the constraints given in 7.3, the
procedure defined in 7.4 shall be followed. The induced voltage is set in the same way as
described in 6.4.1. In addition, the resulting current shall be monitored and corrected for. In this
procedure, a lower common mode impedance may be used, but the common mode current is
limited to the value which would flow from a 150 Ω source.

– 14 – 61000-4-6 © IEC:2008
6.2.2.1 Current clamp
This device establishes an inductive coupling to the cable connected to the EUT. For example,
with a 5:1 turn ratio, the transformed common-mode series impedance can be neglected with
respect to the 150 Ω established by the auxiliary equipment. In this case, the test generator's
output impedance (50 Ω) is transformed into 2 Ω. Other turns ratios may be used; see
Annex A.
NOTE 1 When using a current clamp, care should be taken that the higher harmonics generated by the power
amplifier (PA) do not appear at higher levels than the fundamental signal levels at the EUT port of the coupling
device.
NOTE 2 It is commonly necessary to position the cable through the center of the clamp to minimize capacitive
coupling.
6.2.2.2 EM clamp
The EM clamp establishes both capacitive and inductive coupling to the cable connected to the
EUT. The construction and performance of the EM clamp are described in Annex A.
6.2.3 Direct injection devices
The disturbing signal, coming from the test generator, is injected on to screened and coaxial
cables via a 100 Ω resistor (even if the shield is ungrounded or grounded at one end only). In
between the auxiliary equipment (AE) and the injection point, a decoupling circuit (see 6.2.4)
shall be inserted as close as possible to the injection point (see Figure 5b). To increase
decoupling and to stabilize the circuit, a ground connection shall be made from the screen of
the direct injection device’s input port to the ground reference plane. This connection is made
on the AE side of the injection device.
NOTE When making direct connection to foil shields, caution needs to be exercised to ensure a good connection
producing reliable test results.
For certain simple screened cable configurations, the decoupling circuit together with the
100 Ω resistor may be combined into one box, creating a CDN.
6.2.4 Decoupling networks
Normally, the decoupling network comprises several inductors to create a high impedance over
the frequency range. This is determined by the ferrite material used, and an inductance of at
least 280 μH is required at 150 kHz. The reactance shall remain high, ≥260 Ω up to 26 MHz
and ≥150 Ω above 26 MHz. The inductance can be achieved either by having a number of
windings on ferrite toroids (see Figure 5d) or by using a number of ferrite toroids over the cable
(usually as a clamp-on tube).
The CDNs as specified in Annex D can be used as decoupling networks with the RF input port
left unloaded, unless stated otherwise elsewhere in this standard. When CDNs are used in this
way, they shall meet the requirements of this clause.
The decoupling networks shall be used on all cables not selected for the test, but connected to
the EUT and/or AEs. For exceptions, see 7.7.
6.3 Verification of the common mode impedance at the EUT port of coupling and
decoupling devices
Coupling and decoupling devices are characterized by the common-mode impedance seen at
the EUT port, |Z |. Its correct value ensures the reproducibility of the test results. The
ce
common-mode impedance of coupling and decoupling devices is verified using the set-up
shown in Figure 7.
The coupling and decoupling devices and the impedance reference plane (Figure 7a) shall be
placed on a ground reference plane. The size of the ground reference plane shall exceed the
projected geometry of the set-up on all sides by at least 0,2 m.

61000-4-6 © IEC:2008 – 15 –
The impedance reference plane shall be connected to the EUT port of the CDN by a
connection shorter than or equal to 30 mm as shown in Figure 7a. The magnitude of the
common-mode impedance seen at the connector on the impedance plane shall be measured.
The coupling and decoupling networks shall meet the impedance requirements of Table 3 while
the input port is terminated with a 50 Ω load and the AE-port is sequentially loaded in common-
mode with a short-circuit and an open-circuit condition as shown in Figure 7b. This requirement
ensures sufficient attenuation and makes the set-up of the auxiliary equipment, e.g. open or
short circuited, inpu
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