SIST EN 55016-1-3:2007

SLOVENSKI SIST EN 55016-1-3:2007

STANDARD
marec 2007
Specifikacija merilnih naprav in metod za merjenje radijskih motenj in
odpornosti - 1-3. del: Merilne naprave za merjenje radijskih motenj in
odpornosti - Pomožna oprema – Moč motenj (CISPR 16-1-3:2004)
Specification for radio disturbance and immunity measuring apparatus and
methods - Part 1-3: Radio disturbance and immunity measuring apparatus -
Ancillary equipment - Disturbance power (CISPR 16-1-3:2004)
ICS 17.220.20; 33.100.20 Referenčna številka
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

EUROPEAN STANDARD
EN 55016-1-3
NORME EUROPÉENNE
November 2006
EUROPÄISCHE NORM
ICS 33.100.10;33.100.20 Supersedes EN 55016-1-3:2004

English version
Specification for radio disturbance
and immunity measuring apparatus and methods
Part 1-3: Radio disturbance and immunity measuring apparatus -
Ancillary equipment -
Disturbance power
(CISPR 16-1-3:2004)
Spécifications des méthodes  Anforderungen an Geräte
et des appareils de mesure und Einrichtungen sowie Festlegung
des perturbations radioélectriques der Verfahren zur Messung
et de l'immunité aux perturbations der hochfrequenten Störaussendung
radioélectriques (Funkstörungen) und Störfestigkeit
Partie 1-3: Appareils de mesure Teil 1-3: Geräte und Einrichtungen
des perturbations radioélectriques zur Messung der hochfrequenten
et de l'immunité aux perturbations Störaussendung (Funkstörungen)
radioélectriques - und Störfestigkeit -
Matériels auxiliaires - Zusatz-/Hilfseinrichtungen -
Puissance perturbatrice Störleistungsmessung
(CISPR 16-1-3:2004) (CISPR 16-1-3:2004)

This European Standard was approved by CENELEC on 2006-07-01. 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, 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: rue de Stassart 35, B - 1050 Brussels

© 2006 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 55016-1-3:2006 E
Foreword
The text of the International Standard CISPR 16-1-3:2004, prepared by CISPR SC A, Radio-interference
measurements and statistical methods, was submitted to the CENELEC Unique Acceptance Procedure
and was approved by CENELEC as EN 55016-1-3 on 2006-07-01.

This European Standard supersedes EN 55016-1-3:2004.

In this EN 55016-1-3:2006, a more detailed calibration method for the absorbing clamp is specified.
Furthermore, new alternative calibration methods are introduced which are more practicable than the one
that was specified previously. Additional parameters to describe the absorbing clamp are defined, like the
decoupling factor for the broadband absorber (DF) and the decoupling factor for the current transformer
(DR), along with their validation methods. A procedure for the validation of the absorbing clamp test site
(ACTS) is also included in the document.

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) 2007-07-01

– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2009-07-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard CISPR 16-1-3:2004, including the corrigendum February 2006, was
approved by CENELEC as a European Standard without any modification.
__________
- 3 - EN 55016-1-3:2006
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

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.

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

CISPR 16-1-2 2003 Specification for radio disturbance and EN 55016-1-2 2004
immunity measuring apparatus and methods
Part 1-2: Radio disturbance and immunity
measuring apparatus - Ancillary equipment -
Conducted disturbances
CISPR 16-2-2 2003 Specification for radio disturbance and EN 55016-2-2 2004
immunity measuring apparatus and methods
Part 2-2: Methods of measurement of
disturbances and immunity - Measurement of
disturbance power
1) 2)
CISPR 16-4-2 - Specification for radio disturbance and EN 55016-4-2 2004
immunity measuring apparatus and methods
Part 4-2: Uncertainties, statistics and limit
modelling - Uncertainty in EMC
measurements
IEC 60050-161 1990 International Electrotechnical Vocabulary - -
+ A1 1997 (IEV) - Chapter 161: Electromagnetic - -
+ A2 1998 compatibility - -
1)
Undated reference.
2)
Valid edition at date of issue.

INTERNATIONAL
CISPR
ELECTROTECHNICAL
16-1-3
COMMISSION
Second edition
2004-06
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE
Specification for radio disturbance and immunity
measuring apparatus and methods –
Part 1-3:
Radio disturbance and immunity measuring
apparatus – Ancillary equipment –
Disturbance power
 IEC 2004 Copyright - all rights reserved
No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical,
including photocopying and microfilm, without permission in writing from the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch Web: www.iec.ch
PRICE CODE
V
Commission Electrotechnique Internationale
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МеждународнаяЭлектротехническаяКомиссия
For price, see current catalogue

CISPR 16-1-3  IEC:2004 – 3 –
CONTENTS
FOREWORD.5

1 Scope.9
2 Normative references.9
3 Terms, definitions and abbreviations .9
4 Absorbing clamp instrumentation.11

Annex A (informative) Construction of the absorbing clamp (Subclause 4.2) .35
Annex B (normative) Calibration and validation methods for the absorbing clamp and
the secondary absorbing device (Clause 4).39
Annex C (normative) Validation of the absorbing clamp test site (Clause 4) .59

Figure 1 – Overview of the absorbing clamp measurement method and the associated
calibration and validation procedures.27
Figure 2 – Schematic overview of the absorbing clamp test method.31
Figure 3 – Schematic overview of the clamp calibration methods .33
Figure A.1 – The absorbing clamp assembly and its parts.35
Figure A.2 – Example of the construction of an absorbing clamp.37
Figure B.1 – The original calibration site .51
Figure B.2 – Position of guide for centering the lead under test .51
Figure B.3 – Side view of the calibration jig .53
Figure B.4 – Top view of the jig .53
Figure B.5 – View of the jigs vertical flange .53
Figure B.6 – Test set-up for the reference device calibration method .55
Figure B.7 – Specification of the reference device .55
Figure B.8 – Measurement set-up of the decoupling factor DF .57
Figure B.9 – Measurement set-up of the decoupling factor DR.57
Figure C.1 – Test set-ups for the site attenuation measurement for clamp site
validation using the reference device .63

Table 1 – Overview of the characteristics of the three-clamp calibration methods and
their relation .29

CISPR 16-1-3  IEC:2004 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE
___________
SPECIFICATION FOR RADIO DISTURBANCE AND IMMUNITY
MEASURING APPARATUS AND METHODS –

Part 1-3: Radio disturbance and immunity measuring apparatus –
Ancillary equipment – Disturbance power

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, Publicly Available Specifications (PAS) 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 CISPR 16-1-3 has been prepared by CISPR subcommittee A: Radio
interference measurements and statistical methods.
This second edition cancels and replaces the first edition published in 2003. It constitutes a
technical revision. In this edition a more detailed calibration method for the absorbing clamp is
specified. Furthermore, new alternative calibration methods are introduced which are more
practicable than the one which was specified previously. Additional parameters to describe
the absorbing clamp are defined, like the decoupling factor for the broadband absorber (DF)
and the decoupling factor for the current transformer (DR), along with their validation
methods. A procedure for the validation of the absorbing clamp test site (ACTS) is also
included in the document.
CISPR 16-1-3 © IEC:2004 – 7 –
The text of this standard is based on the following documents:
FDIS Report on voting
CISPR/A/517/FDIS CISPR/A/532/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 this publication 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.
The contents of the corrigendum of February 2006 have been included in this copy.

CISPR 16-1-3  IEC:2004 – 9 –
SPECIFICATION FOR RADIO DISTURBANCE AND IMMUNITY
MEASURING APPARATUS AND METHODS –

Part 1-3: Radio disturbance and immunity measuring apparatus –
Ancillary equipment – Disturbance power

1 Scope
This part of CISPR 16 is designated a basic standard, which specifies the characteristics and
calibration of the absorbing clamp for the measurement of radio disturbance power in the
frequency range 30 MHz to 1 GHz.
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.
CISPR 16-1-2:2003, Specification for radio disturbance and immunity measuring apparatus
and methods – Part 1-2: Radio disturbance and immunity measuring apparatus – Ancillary
equipment – Conducted disturbances
CISPR 16-2-2:2003, Specification for radio disturbance and immunity measuring apparatus
and methods – Part 2-2: Methods of measurement of disturbances and immunity –
Measurement of disturbance power
CISPR 16-4-2, Specification for radio disturbance and immunity measuring apparatus and
methods – Part 4-2: Uncertainties, statistics and limit modelling – Uncertainty in EMC
measurements
IEC 60050-161:1990, International Electrotechnical Vocabulary (IEV) – Chapter 161: Electro-
magnetic compatibility
Amendment 1 (1997)
Amendment 2 (1998)
3 Terms, definitions and abbreviations
3.1 Terms and definitions
See IEC 60050-161, where applicable.
3.2 Abbreviations
ACA Absorbing clamp assembly
ACMM Absorbing clamp measurement method
ACRS Absorbing clamp reference site
ACTS Absorbing clamp test site
CF Clamp factor
CISPR 16-1-3  IEC:2004 – 11 –
CRP Clamp reference point
DF Decoupling factor
DR Decoupling factor that specifies the decoupling of the current transformer from the
common mode impedance of the measurement receiver
JTF Jig transfer factor
LUT Lead under test
RTF Reference transfer factor
SAD Secondary absorbing device
SAR Semi-anechoic room
SRP Slide reference point
4 Absorbing clamp instrumentation
4.1 Introduction
The measurement of disturbance power using an absorbing clamp is a method for the
determination of the radiated disturbance in the frequency range above 30 MHz. This
measurement method represents an alternative approach to the measurement of the
disturbance field strength on an OATS. The absorbing clamp measurement method (ACMM) is
described in Clause 7 of CISPR 16-2-2.
The ACMM uses the following measurement instrumentation:
– the absorbing clamp assembly;
– the secondary absorbing device;
– the absorbing clamp test site.
Figure 1 gives an overview of the absorbing clamp measurement method including the
instrumentation required for this method and the calibration and validation methods for the
instrumentation. The requirements for the instrumentation necessary for the ACMM are
specified in this clause. Details of the absorbing clamp calibration method, and validation of
other properties of the clamp and the secondary absorbing device, are described in Annex B.
Details of the absorbing clamp test site validation are described in Annex C. Absorbing
clamps are suitable for the measurement of disturbances from some types of equipment,
depending on construction and size. The precise measuring procedure and its applicability is
to be specified for each category of equipment. If the EUT itself (without connecting leads)
has a dimension that approaches 1/4 of the wavelength, direct cabinet radiation may occur.
The disturbance capability of an appliance having a mains lead as the only external lead may
be taken as the power the appliance could supply to its mains lead, which acts as a
transmitting antenna. This power is nearly equal to that supplied by the appliance to a
suitable absorbing device placed around the lead at the position where the absorbed power is
at a maximum. Direct radiation from the appliance is not taken into account. Equipment
having external leads other than a mains lead can radiate disturbance energy from such
leads, whether shielded or unshielded, in the same manner as radiation from the mains lead.
Measurements using the absorbing clamp can be made on these types of lead as well.
The application of the ACMM is specified in more detail in 7.9 of CISPR 16-2-2.

CISPR 16-1-3  IEC:2004 – 13 –
4.2 The absorbing clamp assembly
4.2.1 Description of the absorbing clamp assembly
Annex A describes the construction of the clamp and gives a typical example of such a
construction.
The absorbing clamp assembly consists of the following five parts:
– a broadband RF current transformer;
– a broadband RF power absorber and impedance stabilizer for the lead under test;
– an absorbing sleeve and assembly of ferrite rings to reduce RF current on the surface of
the coaxial cable from the current transformer to the measuring receiver;
– a 6 dB attenuator between the output of the absorbing clamp and the coaxial cable
connecting to the measuring receiver;
– a coaxial cable as receiver cable.
The clamp reference point (CRP) indicates the longitudinal position of the front of the current
transformer within the clamp. This reference point is used to define the position of the clamp
during the measurement procedure. The CRP shall be indicated on the outside housing of the
absorbing clamp.
4.2.2 The clamp factor and the clamp site attenuation
An actual measurement of an EUT using the ACMM is depicted schematically in Figure 2.
Details on the ACMM are given in Clause 7 of CISPR 16-2-2.
The disturbance power measurement is based on measurement of the asymmetrical current
generated by the EUT, which is measured at the input of the absorbing clamp using a current
probe. The absorbing ferrites of the clamp around the lead under test isolate the current
transformer from disturbances on the mains. The maximum current is determined by moving
the absorbing clamp along the stretched lead, which acts as a transmission line. The
transmission line transforms the input impedance of the absorbing clamp to the output of the
EUT. At the point of optimal adjustment, the maximum disturbance current at the current
probe or the maximum disturbance voltage at the receiver input can be measured.
For this situation the actual clamp factor CF of an absorbing clamp relates the output signal
act
of the clamp V to the measurand of interest, i.e. the disturbance power P of an EUT as
rec eut
follows:
P = CF + V (1)
eut act rec
where
P = the disturbance power of the EUT in dBpW;
eut
V = the measured voltage in dBμV;
rec
CF = the actual clamp factor in dBpW/μV.
act
Ideally, the received power level P in dBpW at the receiver input can be calculated using
rec
the following formula:
P =V − 10 ⋅ log()Z = V − 17 (2)
rec rec i rec
CISPR 16-1-3  IEC:2004 – 15 –
where
Z = 50 Ω, input impedance of the measuring receiver, and
i
V = measured voltage level in dBμV.
rec
Using Equations (1) and (2) one can derive a relation between the disturbance power P
eut
emitted by the EUT and the power P received by the receiver as follows:
rec
17P − P = CF + (3)
eut rec act
This ideal relation between the disturbance power of the EUT and the power received by the
measuring receiver is defined as the actual clamp site attenuation A (in dB).
act
17A ≡ P − P = CF + (4)
act eut rec act
This actual clamp site attenuation depends on three properties:
– the clamp response properties,
– the site properties and
– the EUT properties.
4.2.3 Decoupling functions of the absorbing clamp
Whereas the current transformer of the absorbing clamp measures the disturbance power, the
decoupling attenuation of the ferrites around the lead under test establishes an asymmetrical
impedance and separates the current transformer from the far end of the lead under test. This
separation reduces the disturbing influence of the connected mains and of the impedance of
the far end and its influence on the measured current. This decoupling attenuation is called
the decoupling factor (DF).
A second decoupling function is needed for the absorbing clamp. The second decoupling
function is the decoupling of the current transformer from the asymmetrical (or common
mode) impedance of the receiver cable. This decoupling is achieved by the absorbing section
of ferrite rings on the cable from the current transformer to the measurement receiver. This
decoupling attenuation is called the decoupling factor to the measurement receiver (DR).
4.2.4 Requirements for the absorbing clamp assembly (ACA)
Absorbing clamps used for disturbance power measurements shall meet the following
requirements:
a) The actual clamp factor (CF ) of the absorbing clamp assembly, as defined in 4.2.1 shall
act
be determined in accordance with the normative methods described in Annex B. The
uncertainty of the clamp factor shall be determined in accordance with the requirements
given in Annex B.
b) The decoupling factor (DF) of the broadband RF absorber and the impedance stabilizer for
the lead under test shall be verified in accordance with the measurement procedure as
described in Annex B. The decoupling factor shall be at least 21 dB for the whole
frequency range.
c) The decoupling function from the current transformer to the measuring output (DR) of the
absorbing clamp shall be determined in accordance with the measurement procedure as
described in Annex B. The decoupling factor to the measurement receiver shall be at least
30 dB for the whole frequency range. The 30 dB contains 20,5 dB attenuation from the
absorbing clamp and 9,5 dB from the coupling/decoupling network (CDN).

CISPR 16-1-3  IEC:2004 – 17 –
d) The length of the clamp housing shall be 600 mm ± 40 mm.
e) A 50 Ω RF attenuator of at least 6 dB shall be used directly at the clamp output.
4.3 The absorbing clamp assembly calibration methods and their relations
The purpose of the clamp calibration is to determine the clamp factor CF in a situation that
resembles an actual measurement with an EUT as much as possible. However, in 4.2.2 it is
stated that the clamp factor is a function of the EUT, the clamp properties and the site
performance. For standardization (reproducibility) reasons, the calibration method shall use a
test site with a specified and reproducible performance, and a signal generator and receiver
with reproducible performance. Under these conditions, the only variable left is the absorbing
clamp under consideration.
Three absorbing clamp calibration methods are developed below, each with their own
advantages, disadvantages and applications (see Table 1). Figure 3 gives a schematic
overview of the three possible methods.
In general, each of the calibration methods comprises the following two steps.
First, as a reference, the output power P of the RF generator (with 50 Ω output impedance)
gen
is measured directly through a 10 dB attenuator using a receiver (Figure 3a). Secondly, the
disturbance power of the same generator and 10 dB attenuator is measured through the
clamp using one of the following three possible methods.
a) The original method
The original absorbing clamp set-up calibration method uses a reference site including a
large vertical reference plane (Figure 3b). By definition this method gives the CF directly,
because this is the original calibration method, which is used for the determination of the
limits and therefore considered as the reference. The lead under test is connected to the
centre conductor of the feed-through connector in the vertical reference plane. At the back
of this vertical plane, the feed-through connector is connected to the generator. For this
calibration configuration, P is measured while the clamp is moved along the lead under
orig
test, in accordance with the procedure described in Annex B such that for each frequency
the maximum value is obtained. The minimum site attenuation A and the absorbing
orig
clamp factor CF can be determined using the following equations:
orig
A = P − P                        (5)
orig gen orig
and
CF = A − 17                           (6)
orig orig
The minimum site attenuation A is in the range of about 13 dB to 22 dB.
orig
b) The jig calibration method
The jig calibration method uses a jig that can be adapted to the length of the absorbing
clamp under calibration and the secondary absorbing device (SAD). This jig serves as a
reference structure for the absorbing clamp (see Figure 3c). For this calibration
configuration P is measured as a function of frequency while the clamp is in a fixed
jig
position within the jig. The site attenuation A and the absorbing clamp factor CF can
jig jig
be determined using the following equations:

CISPR 16-1-3  IEC:2004 – 19 –
A = P – P (7)
jig gen jig
and
CF = A – 17                             (8)
jig
c) The reference device method
The reference device method uses a reference site (without vertical reference plane) and
a reference device that is fed through the lead under test, which is a coaxial structure for
this purpose (see Figure 3d).
For this calibration configuration, P is measured while the absorbing clamp is moved
ref
along the lead under test in accordance with the procedure described in Annex A such that
for each frequency the maximum value is obtained. The minimum site attenuation A and
ref
the absorbing clamp factor CF can be determined using the following equations:
ref
A = P – P (9)
ref gen ref
and
CF = A – 17                          (10)
ref ref
Annex B describes the three possible absorbing clamp calibration methods in more detail. A
survey of the three clamp calibration methods is also given in Figure 1. Figure 1 also gives
the relation of the clamp measurement method and the clamp calibration methods and the
role of the reference site.
NOTE Calibration takes place on clamp, attenuator and cable. They have to be held together.
The absorbing clamp factors obtained through the jig method and the reference device
method (CF , CF ) differ systematically from the original absorbing clamp factor CF . It is
jig ref orig
necessary to establish this systematic relation between these different clamp factors as
follows.
The jig transfer factor JTF is calculated by
JTF = CF – CF (11)
jig orig
The JTF in dB is to be determined for each type of absorbing clamp by the clamp
manufacturer. The manufacturer or an accredited calibration laboratory in charge shall
determine the JTF by averaging the results of at least five reproduced calibrations for five
devices of a production series. Similarly, the reference transfer factor RTF is determined by
RTF = CF – CF                         (12)
ref orig
Again, the RTF in dB is to be determined for each type of absorbing clamp by the clamp
manufacturer. The manufacturer or an accredited calibration laboratory in charge shall
determine the RTF by averaging the results of at least five reproduced calibrations for five
devices of a production series.
In summary, the original calibration method directly gives the value of CF . The jig and the
orig
reference device method give the CF and the CF respectively, from which the original
jig ref
absorbing clamp factor can be calculated using Equations (11) and (12).

CISPR 16-1-3  IEC:2004 – 21 –
4.4 The secondary absorbing device
In addition to the absorbing part of the clamp, a secondary absorbing device (SAD) directly
behind the absorbing clamp shall be applied to reduce the uncertainty of the measurement.
The function of this SAD is to provide an attenuation in addition to that provided by the
decoupling attenuation of the absorbing clamp. The SAD shall be moved in the same way as
the absorbing clamp during the calibration and measurement. Therefore the SAD needs
wheels to accommodate the scanning. The SAD dimensions shall be such that the lead under
test is at the same height as in the absorbing clamp.
The decoupling factor of the SAD shall be verified in accordance with the measurement
procedure as described in Annex B. The decoupling factor for the SAD is measured together
with the absorbing clamp.
NOTE New technologies may make it possible for the additional functionality of the SAD to be integrated in the
absorbing clamp. Consequently, if the absorbing clamp itself meets the decoupling factor specification, then the
SAD does not need to be applied.
4.5 The absorbing clamp test site (ACTS)
4.5.1 Description of the ACTS
The absorbing clamp test site (ACTS) is a site used for application of the ACMM. The ACTS
can be either an outdoor or an indoor facility and includes the following elements (see
Annex C, Figure C.1):
– the EUT table, which is a support for the EUT unit;
– the clamp slide, which is a support for the connected lead of the EUT (or lead under test,
LUT) and for the absorbing clamp ;
– a gliding support for the receiver cable of the absorbing clamp;
– auxiliary means like a rope to move the absorbing clamp
All the above-mentioned ACTS elements (without EUT table) shall be measured in the ACTS
validation procedure.
The near end of the clamp slide (at the side of the EUT) is denoted as the slide reference
point (SRP, see Figure C.1). This SRP is used to define the horizontal distance to the CRP of
the clamp.
4.5.2 The functions of the ACTS
The ACTS has the following functions.
a) Physical function: to provide specific supporting means for the EUT and the LUT.
b) Electrical function: to provide an ideal (for RF) site for the EUT and the clamp assembly
and to provide a well-defined measurement environment for application of the absorbing
clamp (no distortion of emissions by walls or by the supporting elements like the EUT
table, the clamp slide, gliding support and rope).
4.5.3 Requirements for the ACTS
The following requirements apply for the ACTS:
a) The length of the clamp slide shall ensure that the absorbing clamp can be moved over a
distance of 5 m. This means that the clamp slide shall have a length of 6 m.

CISPR 16-1-3 © IEC:2004 – 23 –
NOTE For reproducibility reasons, the length of the clamp slide and the scanning distance of the clamp are
fixed to at least 6 m and 5 m respectively. The length of the clamp slide is determined by the sum of the
scanning length (5 m), the margin between the SRP and the CRP (0,15 m) and the length of the absorbing
clamp (0,64 m) plus a margin to accommodate lead fixtures at the end (0,1 m). This totals a length of 6 m for
the clamp slide.
b) The height of the clamp slide shall be 0,8 m ± 0,05 m. This implies that within the
absorbing clamp and within the SAD, the height of the LUT above the reference plane will
be a few centimetres larger.
c) The material of the EUT table and of the clamp slide shall be non-reflecting, non-
conducting and the dielectric properties may be close to the dielectric properties of air. In
this way, the EUT table is transparent from an electromagnetic point of view.
d) The material of the rope used to move the clamp along the clamp slide shall also be
transparent from an electromagnetic point of view.
NOTE The influence of the material of the EUT table and the clamp slide may be significant for frequencies
above 300 MHz.
e) The adequacy of the site (see the electrical ACTS function) is validated by comparing the
in-situ measured clamp factor of the ACTS (CF ) with the clamp factor measured on
in-situ
the absorbing clamp reference site (ACRS) (CF ) using the original calibration method
orig
(see Annex C). The absolute difference between both clamp factors shall comply with the
following requirement:
∆ = CF – CF (13)
ACTS orig in-situ
shall be
<2,5 dB between 30 MHz and 150 MHz,
2,5 dB to 2 dB between 150 MHz and 300 MHz, decreasing and
<2 dB between 300 MHz and 1 000 MHz
This site validation procedure is specified in more detail in the next subclause.
4.5.4 Validation methods for the ACTS
The characteristics for the ACTS are validated as follows.
– The physical requirements 4.5.3a) and 4.5.3b) can be validated by inspection.
– The electrical function of the ACTS (requirement 4.5.3e) shall be validated by comparing
the clamp factor CF of the calibrated clamp with the clamp factor CF measured in-
in-situ
situ, in accordance with the ”original calibration method” (see Annex C).
Investigations have shown that a 10 m OATS or SAR validated for radiated emission
measurements can be considered as an ideal site for performing the ACMM. Therefore, a
validated 10 m OATS or SAR is adopted as a reference site for electrical validation of the
ACTS. Consequently, if a validated 10 m OATS or SAR is used as a clamp test site, then the
electrical function of this site does not need to be validated further.
The validation procedure of the electrical function of a clamp test site is described in detail in
Annex C.
CISPR 16-1-3  IEC:2004 – 25 –
4.6 Quality assurance procedures for the absorbing clamp instrumentation.
4.6.1 Overview
The performance of an absorbing clamp and secondary absorbing device may change over
time due to use, aging or defects. Similarly, the ACTS performance may change due to
modifications in the construction or by aging.
The jig calibration method and the reference device calibration method can be used
conveniently for quality assurance procedures, provided that the jig clamp factor and the
reference device clamp factor are initially known.
4.6.2 Quality assurance check for the ACTS
The data of the site attenuation A of the ACTS determined at the time the site was validated
ref
can be used as a reference.
After a certain time interval and after modification of the site, this site attenuation
measurement can be repeated, and the results compared with the reference data.
The advantage of this method is that all elements of the ACMM are evaluated at once.
4.6.3 Quality assurance check for the absorbing clamp
The decoupling functions and the clamp factor performance determined at the time the clamp
has been validated can be used as reference performance data.
After certain time intervals or after a change made to the site, these performance parameters
can be verified again by measuring the decoupling factors and by measuring the clamp factor
using the jig method (Annex B).
4.6.4 Quality assurance pass/fail criteria
The pass/fail criteria for the quality assurance tests are related to the measurement
uncertainty of the measurement parameter in question. This means that a change of the
parameter in question is acceptable if this change is less than one times the measurement
uncertainty.
CISPR 16-1-3  IEC:2004 – 27 –
ABSORBING CLAMP MEASUREMENT
METHOD (ACMM)
(CISPR 16-2-2 Clause 7)
Requires:
• EUT
• a calibrated clamp
• a validated abs. clamp test site (ACTS)
• a calibrated receiver
VALIDATION OF THE ABS CLAMP TEST SITE

• specified test set-up
(ACTS)
• specified test procedure
(specified in Annex C)
Gives: disturbance power of an EUT

Requires:
• the ACTS (absorbing clamp test site) under

validation
• a calibrated clamp with the SAD calibrated with

the original method
• a calibrated receiver
CLAMP CALIBRATION METHODS
(specified in Annex B)
• a specific test set-up
a. Validation of the clamp
• a specific test procedure
Requires:
Gives: a validated test absorbing clamp test site
The validation of the decoupling functions of the
clamp with the secondary absorbing device

b. The original method
Requires:
• the clamp under calibration with the SAD
VALIDATION OF DECOUPLING
• measurement equipment
FUNCTIONS OF THE
• a validated site: ACRS (absorbing clamp reference
ABSORBING CLAMP WITH THE
site)
SECONDARY DEVICE (Annex B)
• a specified source (generator + large vertical

reference plane)
Requires:
• a specified test set-up
• the clamp with the SAD
• a specified test procedure
• a jig
Gives: the original clamp factor (CF )
orig
• a specified source
• measurement equipment
c. The jig method
• specified test setup
Requires:
• specified test procedure
• the clamp under calibration with the SAD

• measurement equipment
• a calibration jig
• a specified source
• a specified test set-up
• a specified test procedure
Gives: the clamp factor CF and CF can be
jig orig
calculated using the jig transfer factor JTF.
ABS CLAMP REFERENCE SITE (ACRS)

d. The reference device method

A 10 m OATS or SAR, validated for radiated
Requires:
emission measurements between 30 MHz and
• the clamp under calibration with the SAD
1 000 MHz is considered also valid as a site for

• measurement equipment
clamp calibration.
• a validated site: ACRS (absorbing clamp reference

site)
• the clamp reference device
• a specified test set-up
• a specified test procedure
Gives: the clamp factor CF and CF can be
ref orig
calculated using the reference transfer factor RTF.

IEC  830/04
Figure 1 – Overview of the absorbing clamp measurement method and the associated
calibration and validation procedures

CISPR 16-1-3  IEC:2004              – 29 –

Table 1 – Overview of the characteristics of the three-clamp calibration methods and their relation
Name of the
Test Site used EUT used Applications
Advantages (+), disadvantages (-) and remarks (••••)
calibration method
The original method An absorbing Large vertical reference plane • Calibration set-up resembles an actual measurement Direct calibration of the
clamp reference and fed behind this reference absorbing clamp
with a large EUT
site plane by a generator
– Handling of the large vertical reference plane is
laborious
– A reference site (ACRS) required
+ By definition this method gives the CF directly
because this method is the original calibration method
and therefore considered as the reference
Indirect calibration of the
The jig method An absorbing One of the vertical flanges of the – Calibration set-up does not resemble an actual test
clamp calibration jig and fed behind this jig flange absorbing clamp
+ Convenient handling
jig by a generator
Quality assurance check
+ No reference site (ACRS) required
of the clamp
+ Good reproducibility
– Does not give the CF directly; CF is calculated using
the JTF
The reference device An absorbing Small reference device fed from Indirect calibration of the
• Calibration set-up resembles an actual measurement
method clamp reference the far end by a generator absorbing clamp
with a large EUT
site
+ Reference device easy to handle Validation of the ACTS

– A reference site (ACRS) required Quality assurance check
of the overall clamp
– Does not give the CF directly; CF is calculated using
measurement set-up
the RTF
NOTE An ACRS is a validated 10 m OATS or SAR facility.

CISPR 16-1-3  IEC:2004 – 31 –

EUT
P
eut
Absorbing
clamp
Lead under test
CF
act
V (P )
rec rec
IEC  831/04
Horizontal floor of the clamp test site

Key
P the disturbance power of the EUT in dBpW;
eut
V the measured voltage in dBμV;
rec
CF the actual clamp factor in dBpW/μV;
act
P the received power level in dBpW.
rec
Figure 2 – Schematic overview of the absorbing clamp test method

CISPR 16-1-3  IEC:2004 – 33 –

P
gen
Receiver
Generator
(50 Ω)
10 dB
attenuator
IEC  832/04
Figure 3a
Large vertical reference plane
Absorbing   Secondary
Generator
clamp absorbing device
10 dB
attenuator
CF
orig
P
orig
Horizontal reference plane of the reference site IEC  833/04

Figure 3b
jig
CF
jig
Absorbing   Secondary
Generator
clamp absorbing device
50 Ω
10 dB
attenuator
P
jig
IEC  834/04
Figure
...