CISPR 16-1-4:2025

CISPR 16-1-4 ®
Edition 5.0 2025-10
INTERNATIONAL
STANDARD
REDLINE VERSION
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE

Specification for radio disturbance and immunity measuring apparatus and
methods -
Part 1-4: Radio disturbance and immunity measuring apparatus - Antennas and
test sites for radiated disturbance measurements
ICS 33.100.10; 33.100.20 ISBN 978-2-8327-0762-3
All rights reserved. Unless otherwise specified, 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 either
IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC copyright
or have an enquiry about obtaining additional rights to this publication, please contact the address below or your local
IEC member National Committee for further information.

IEC Secretariat Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.

IEC publications search - IEC Products & Services Portal - products.iec.ch
webstore.iec.ch/advsearchform Discover our powerful search engine and read freely all the
The advanced search enables to find IEC publications by a publications previews, graphical symbols and the glossary.
variety of criteria (reference number, text, technical With a subscription you will always have access to up to date
committee, …). It also gives information on projects, content tailored to your needs.
replaced and withdrawn publications.
Electropedia - www.electropedia.org
The world's leading online dictionary on electrotechnology,
IEC Just Published - webstore.iec.ch/justpublished
Stay up to date on all new IEC publications. Just Published containing more than 22 500 terminological entries in English
details all new publications released. Available online and and French, with equivalent terms in 25 additional languages.
once a month by email. Also known as the International Electrotechnical Vocabulary
(IEV) online.
IEC Customer Service Centre - webstore.iec.ch/csc
If you wish to give us your feedback on this publication or
need further assistance, please contact the Customer
Service Centre: sales@iec.ch.
CONTENTS
FOREWORD . 9
1 Scope . 1
2 Normative references . 11
3 Terms, definitions and abbreviated terms . 12
3.1 Terms and definitions. 12
3.2 Abbreviated terms . 18
4 Antennas for measurement of radiated radio disturbance . 19
4.1 General . 19
4.2 Physical parameter (measurand) for radiated disturbance measurements . 19
4.3 Antennas for the frequency range 9 kHz to 150 kHz . 19
4.3.1 General . 19
4.3.2 Magnetic field antenna. 19
4.3.3 Shielding of loop antenna . 21
4.4 Antennas for the frequency range 150 kHz to 30 MHz . 21
4.4.1 Electric field antenna . 21
4.4.2 Magnetic field antenna. 21
4.4.3 Balance and electric field discrimination of antennas . 21
4.5 Antennas for the frequency range 30 MHz to 1 000 MHz . 22
4.5.1 General . 22
4.5.2 Low-uncertainty antenna for use if there is an alleged non-compliance

to the electric disturbance field strength limit . 22
4.5.3 Antenna characteristics . 22
4.5.4 Balance of antenna . 24
4.5.5 Cross-polar response of antenna . 25
4.6 Antennas for the frequency range 1 GHz to 18 GHz . 26
4.6.1 General . 26
4.6.2 Receive antenna . 27
4.7 Special antenna arrangements – large-loop antenna system . 29
5 Test sites for measurement of radio disturbance field strength for the frequency
range of 9 kHz to 30 MHz . 30
5.1 General . 30
5.2 Radio-frequency ambient environment of a test site . 30
5.3 Measurement distance and test volume . 30
5.4 Set-up table and antenna positioner . 30
5.5 Validation procedure of test site . 31
5.5.1 General . 31
5.5.2 Normalized site insertion loss (NSIL) . 35
5.5.3 Reference site method . 35
5.5.4 Acceptance criterion . 36
6 Test sites for measurement of radio disturbance field strength for the frequency
range of 30 MHz to 1 000 MHz . 36
6.1 General . 36
6.2 OATS . 37
6.2.1 General . 37
6.2.2 Weather-protection enclosure . 37
6.2.3 Obstruction-free area . 37
6.2.4 Radio-frequency ambient environment of a test site . 38
6.2.5 Ground plane . 39
6.3 Suitability of other test sites . 39
6.3.1 Other ground-plane test sites . 39
6.3.2 Test sites without ground plane (FAR) . 39
6.4 Test site validations . 40
6.4.1 General . 40
6.4.2 Overview of test site validations . 40
6.5 Basic parameters of the NSA method for OATS and SAC . 41
6.5.1 General equation and table of theoretical NSA values . 41
6.5.2 Antenna calibration . 45
6.6 Reference site method for OATS and SAC . 45
6.6.1 General . 45
6.6.2 Antennas not permitted for RSM measurements . 45
6.6.3 Determination of the antenna pair reference site attenuation on a
REFTS . 46
6.6.4 Determination of the antenna pair reference site attenuation using an
averaging technique on a large OATS . 47
6.7 Validation of an OATS by the NSA method . 50
6.7.1 Discrete frequency method . 50
6.7.2 Swept frequency method . 51
6.8 Validation of a weather-protection-enclosed OATS or a SAC . 52
6.9 Possible causes for exceeding site acceptability limits . 55
6.10 Site validation for FAR sites . 55
6.10.1 General . 55
6.10.2 RSM for FAR sites . 59
6.10.3 NSA method for FAR sites . 61
6.10.4 Site validation criteria for FAR sites . 63
6.11 Evaluation of set-up table and antenna tower . 63
6.11.1 General . 63
6.11.2 Evaluation procedure for set-up table influences. 64
7 Test sites for measurement of radio disturbance field strength for the frequency
range 1 GHz to 18 GHz . 66
7.1 General . 66
7.2 Reference test site . 66
7.3 Test site validation . 66
7.3.1 General . 66
7.3.2 Acceptance criterion for site validation . 68
7.4 Antenna requirements for S standard test procedure . 68
VSWR
7.4.1 General . 68
7.4.2 Transmit antenna . 68
7.4.3 Antennas and test equipment for the S reciprocal test procedure . 71
VSWR
7.5 Required positions for site validation testing . 72
7.5.1 General . 72
7.5.2 Descriptions of S measurement positions in a horizontal plane
VSWR
(Figure 27). 73
7.5.3 Descriptions of S additional measurement positions (Figure 28) . 74
VSWR
7.5.4 Summary of S measurement positions . 74
VSWR
7.6 S site validation – standard test procedure . 77
VSWR
7.7 S site validation – reciprocal test procedure using an isotropic field
VSWR
probe . 78
7.8 S conditional measurement position requirements . 79
VSWR
7.9 S site validation test report . 80
VSWR
7.10 Limitations of the S site validation method . 81
VSWR
7.11 Alternative test sites . 81
8 Cable termination devices used in radiated emission testing . 81
8.1 Common-mode absorption devices . 81
8.1.1 General . 81
8.1.2 CMAD S-parameter measurements . 82
8.1.3 CMAD test jig . 82
8.1.4 Measurement method using the TRL calibration . 83
8.1.5 Specification of ferrite clamp-type CMAD . 85
8.1.6 CMAD performance (degradation) check using spectrum analyzer and
tracking generator . 86
8.2 VHF-LISN cable termination devices . 88
8.2.1 General . 88
8.2.2 Balanced VHF-LISN . 89
8.2.3 Unbalanced VHF-LISN . 90
8.2.4 Measurement of the VHF-LISN impedance . 92
9 Reverberating chamber for total radiated power measurement . 98
10 TEM waveguides for radiated disturbance measurements . 98
Annex A (normative) Parameters of antennas . 99
A.1 General . 99
A.2 Preferred antennas . 99
A.2.1 General . 99
A.2.2 Calculable antenna . 99
A.2.3 Low-uncertainty antennas . 100
A.3 Simple dipole antennas . 101
A.3.1 General . 101
A.3.2 Tuned dipole. 101
A.3.3 Shortened dipole . 101
A.4 Broadband antenna parameters . 103
A.4.1 General . 103
A.4.2 Antenna type . 103
A.4.3 Specification of the antenna . 103
A.4.4 Antenna calibration . 104
A.4.5 Antenna user information . 104
Annex B (XXX) (Void) .
Annex B (normative) Large-loop antenna system for magnetic field induced-current
measurements in the frequency range of 9 kHz to 30 MHz . 107
B.1 General . 107
B.2 Construction of an LLAS . 107
B.3 Construction of a large-loop antenna (LLA) . 107
B.4 Validation of an LLAS . 112
B.5 Construction of the LLAS verification dipole antenna . 114
B.6 Conversion factors . 115
B.6.1 General . 115
B.6.2 Current conversion factors for an LLAS with non-standard diameter . 116
B.6.3 Conversion of LLAS measured current to magnetic field strength . 117
B.7 Examples . 119
Annex C (normative) Construction details for open area test sites in the frequency
range of 30 MHz to 1 000 MHz (see Clause 6) . 120
C.1 General . 120
C.2 Ground plane construction . 120
C.2.1 Material . 120
C.2.2 Roughness . 120
C.3 Services to EUT . 121
C.4 Weather-protection enclosure construction . 121
C.4.1 Materials and fasteners . 121
C.4.2 Internal arrangements . 122
C.4.3 Size . 122
C.4.4 Uniformity with time and weather . 122
C.5 Turntable and set-up table . 122
C.6 Receive antenna mast installation . 123
Annex D (informative) Basis for the ±4 dB site acceptability criterion (see Clause 6) . 124
D.1 General . 124
D.2 Error analysis . 124
Annex E (XXX) (Void) .
Annex E (informative) Examples of uncertainty budgets for site validation of a COMTS
using RSM with a calibrated antenna pair (see 6.6) . 127
E.1 Quantities to be considered for antenna pair reference site attenuation
calibration using the averaging technique . 127
E.2 Quantities to be considered for antenna pair reference site attenuation
calibration using a REFTS . 128
E.3 Quantities to be considered for COMTS validation using an antenna pair
reference site attenuation . 128
Annex F (informative) Definition of uncertainty in cross-polar response measurement . 130
F.1 General . 130
F.2 Example uncertainty estimate . 133
F.3 Rationale for the estimates of input quantities in Table F.1 and Table F.3 . 134
F.4 Measurement of XPR below 100 MHz at an OATS . 136
Annex G (informative) Measurement uncertainties of COMTS validation results in the
frequency range 9 kHz to 30 MHz . 137
G.1 Quantities to be considered for COMTS validation using the NSIL method . 137
G.2 Quantities to be considered for COMTS validation using the RSM method . 139
Annex H (normative) Derivation of NSIL values in the frequency range 9 kHz to
30 MHz . 142
H.1 General . 142
H.2 Magnetic field antenna factor . 143
H.3 Site insertion loss . 144
H.4 Normalized site insertion loss . 146
H.5 NSIL tables . 149
Annex I (informative) Recommendations for the design of test sites in the frequency
range 9 kHz to 30 MHz . 154
I.1 General . 154
I.2 Dimensions and quality of the ground plane . 154
I.3 Obstruction free area . 155
I.4 Resonance-free area . 155
Annex J (informative) Accuracy of NSIL values in the frequency range of 9 kHz to
30 MHz . 157
J.1 General . 157
J.2 Cross-check of NEC with analytic formulas . 157
J.3 Recommended NEC versions . 158
J.4 Instabilities at the lower frequency end . 159
J.5 Extrapolation methods to solve instabilities . 159
J.6 Reducing the number of segments to solve instabilities . 160
Annex K (informative) Example calculation for 10 m SAC sites that do not fulfil the
±4 dB criterion within 9 kHz to 30 MHz . 161
Annex L (normative) Calibration of the sum of magnetic field antenna factors in the
frequency range of 9 kHz to 30 MHz . 164
L.1 General . 164
L.2 Calibration procedure. 164
L.3 Measurement uncertainties . 165
Bibliography . 167

Figure 1 – Example of size-compliant loop antenna . 20
Figure 2 – Schematic of radiation from EUT reaching an LPDA antenna directly and via
ground reflection at a 3 m site, showing the beamwidth half-angle, ϕ,
at the reflected ray . 24
Figure 3 – RX antenna E-plane radiation pattern example, with limit area shaded for 3
m distance and 2 m EUT width . 28
Figure 4 – Determination of maximum useable EUT width using half-power beamwidth . 29
Figure 5 – General arrangement of the three measurement orientations H , H and H ,
x y z
where d is the measurement distance and h is the height of the reference point . 32
Figure 6 – Antenna positions (top view) . 33
Figure 7 – Antenna positions (3D view) . 34
Figure 8 – Test set-up for V with power amplifier and attenuator . 35
DIRECT
Figure 9 – Obstruction-free area of a test site with a turntable . 38
Figure 10 – Obstruction-free area with stationary EUT . 38
Figure 11 – Test point locations for 3 m and 10 m test distances . 47
Figure 12 – Paired test point locations for all test distances . 49
Figure 13 – Example of paired test point selection for a test distance of 10 m . 49
Figure 14 – Illustration of an investigation of influence of antenna mast on A . 50
APR
Figure 15 – Typical antenna positions for a weather-protected OATS or a SAC –
vertical polarization validation measurements . 53
Figure 16 – Typical antenna positions for a weather-protected OATS or a SAC –
horizontal polarization validation measurements . 53
Figure 17 – Typical antenna positions for a weather-protected OATS or a SAC –
vertical polarization validation measurements for a smaller EUT . 54
Figure 18 – Typical antenna positions for a weather-protected OATS or a SAC –
horizontal polarization validation measurements for a smaller EUT . 54
Figure 19 – Measurement positions for FAR site validation . 57
Figure 20 – Example of one measurement position and antenna tilt for FAR site
validation . 58
Figure 21 – Typical quasi free-space test site reference SA measurement set-up . 60
Figure 22 – Theoretical free-space NSA as a function of frequency for different
measurement distances [see Equation (18)]. 63
Figure 23 – Position of the antenna relative to the edge above a rectangle set-up table
(top view) . 66
Figure 24 – Antenna position above the set-up table (side view) . 66
Figure 25 – Transmit antenna E-plane radiation pattern example (this example is for
informative purposes only) . 69
Figure 26 – Transmit antenna H-plane radiation pattern (this example is for informative
purposes only) . 71
Figure 27 – S measurement positions in a horizontal plane (see 7.5.2 for
VSWR
description) . 72
Figure 28 – S positions (height requirements) . 74
VSWR
Figure 29 – S conditional measurement position requirements . 80
VSWR
Figure 30 – Definition of the reference planes inside the test jig . 83
Figure 31 – The four configurations for the TRL calibration . 85
Figure 32 – Limits for the magnitude of S , measured according to the provisions of
8.1.1 to 8.1.3 . 86
Figure 33 – Example of a 50 Ω adaptor construction in the vertical flange of the jig . 87
Figure 34 – Example of a matching adaptor with balun or transformer . 88
Figure 35 – Example of a matching adaptor with resistive matching network . 88
Figure 36 – Example circuit diagram of a balanced VHF-LISN . 90
Figure 37 – Example circuit diagram of an unbalanced VHF-LISN . 91
Figure 38 – Terminal-to-reference ground impedances of the VHF-LISN at the EUT
mains port . 93
Figure 39 – Example VHF-LISN impedance measurement set-up geometry . 95
Figure 40 – Example IMA . 96
Figure 41 – Connection between the IMA and the VHF-LISN . 97
Figure A.1 – Short dipole antenna factors for R = 50 Ω . 102
L
Figure B.1 – The LLAS, consisting of three mutually perpendicular large-loop antennas . 109
Figure B.2 – An LLA containing two opposite slits, positioned symmetrically with
respect to the current probe C . 110
Figure B.3 – Construction of an LLA slit . 110
Figure B.4 – Example of an LLA slit construction using a strap of printed circuit board
to obtain a rigid construction . 111
Figure B.5 – Construction of the metal box containing the current probe . 111
Figure B.6 – Example showing the routing of several cables from an EUT to minimize
capacitive coupling from the leads to the LLAS . 112
Figure B.7 – The eight positions of the LLAS verification dipole during validation
of an LLA . 113
Figure B.8 – Reference validation factors for loops of 2 m, 3 m, and 4 m diameters . 113
Figure B.9 – Construction of the LLAS verification dipole antenna . 115
Figure B.10 – Sensitivity S of an LLA with diameter D relative to an LLA with 2 m
D
diameter . 117
Figure B.11 – Conversion factor C [for conversion into dB(μA/m)] for three standard
dA
measurement distances d . 118
Figure C.1 – The Rayleigh criterion for roughness in the ground plane . 121
Figure H.1 – Investigation of wire radius, normalized to 0,001 m . 146
Figure H.2 – Investigation of feed point location (not to scale) . 147
Figure H.3 – Variation of NSIL values for various set-ups, for a distance of 3 m, h = 1,3 . 149
Figure H.4 – Specification of feed point location for tabular values (not to scale) . 150
Figure H.5 – Calculation examples, loop diameter 60 cm, feed point location per
Figure H.4 . 152
Figure I.1 – Recommended minimum dimensions of the ground plane (top view) . 154
Figure I.2 – Recommended obstruction free area (top view) . 155
Figure J.1 – Comparison of NSIL values by analytic formulas and computer simulation . 158
Figure K.1 – Example site validation result . 162
Figure K.2 – U calculated from site validation result . 163
lab
Figure K.3 – Frequency-dependent correction factor . 163
Figure L.1 – Antenna arrangement for the sum of antenna factors method . 165

Table 1 – Maximum frequency step size . 32
Table 2 – Acceptance criterion . 36
Table 3 – Site validation methods applicable for OATS, OATS-based, SAC, and FAR
site types . 40
Table 4 – Theoretical normalized site attenuation, A – recommended geometries for
N
a
broadband antennas . 43
Table 5 – Example template for A data sets . 46
APR
Table 6 – RSM frequency steps . 46
Table 7 – Maximum dimensions of test volume versus test distance . 55
Table 8 – Frequency ranges and step sizes for FAR site validation . 57
Table 9 – S measurement position designations . 75
VSWR
Table 10 – S reporting requirements . 80
VSWR
Table 11 – Specifications for the EUT mains port of the balanced VHF-LISN . 89
Table 12 – Specifications for the EUT mains port of the unbalanced VHF-LISN . 91
Table B.1 – Reference validation factors of Figure B.8 for loops of 2 m, 3 m, and 4 m
diameters . 114
Table B.2 – Sensitivity S of an LLA with diameter D relative to an LLA with 2 m
D
diameter (Figure B.10) . 116
Table B.3 – Magnetic field strength conversion factor C for three measurement
dA
distances (Figure B.11) . 119
Table C.1 – Maximum roughness for 3 m, 10 m and 30 m measurement distances . 121
Table D.1 – Error budget . 125
Table E.1 – Antenna pair reference site attenuation calibration using the large-OATS
averaging technique . 127
Table E.2 – Antenna pair reference site attenuation calibration using REFTS . 128
Table E.3 – COMTS validation using an antenna pair reference site attenuation . 129
Table F.1 – Example uncertainty estimate for XPR measurement in a FAR and
assumed a = 22 dB, a = 34 dB . 134
xpT xpR
Table F.2 – Uncertainties depending on other values of A (other assumptions as in
xpT
Table F.1) . 136
Table F.3 – Example uncertainty estimate for XPR measurement at an OATS and
assumed a = 22 dB, a = 34 dB . 136
xpT xpR
Table G.1 – Example measurement uncertainty budget for COMTS validation using the
NSIL method . 137
Table G.2 – Example measurement uncertainty budget for COMTS validation using the
RSM method . 140
Table H.1 – Calculation examples (loop diameter 60 cm, d = 3 m, h = 1,3 m) . 152
Table H.2 – Calculation examples (loop diameter 60 cm, d = 5 m, h = 1,3 m) . 152
Table H.3 – Calculation examples (loop diameter 60 cm, d = 10 m, h = 1,3 m) . 153
Table I.1 – Skin depth for some practical materials at 9 kHz . 155
Table J.1 – Recommended NEC implementations . 159
Table J.2 – Observed instabilities . 159
Table K.1 – Measurement uncertainty of radiated disturbance results from 9 kHz to
30 MHz . 161
Table K.2 – Influence of δA on U . 161
i lab
Table L.1 – Example of an uncertainty budget for sum of antenna factors method . 165

INTERNATIONAL ELECTROTECHNICAL COMMISSION
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE
____________
Specification for radio disturbance and
immunity measuring apparatus and methods -
Part 1-4: Radio disturbance and immunity measuring apparatus -
Antennas and test sites for radiated disturbance measurements

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 itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
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
...