IEC 61000-4-20:2022

IEC 61000-4-20 ®
Edition 3.0 2022-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
BASIC EMC PUBLICATION
PUBLICATION FONDAMENTALE EN CEM
Electromagnetic compatibility (EMC) –
Part 4-20: Testing and measurement techniques – Emission and immunity
testing in transverse electromagnetic (TEM) waveguides

Compatibilité électromagnétique (CEM) –
Partie 4-20: Techniques d’essai et de mesure – Essais d’émission et d’immunité
dans les guides d’onde TEM
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IEC 61000-4-20 ®
Edition 3.0 2022-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
BASIC EMC PUBLICATION
PUBLICATION FONDAMENTALE EN CEM

Electromagnetic compatibility (EMC) –

Part 4-20: Testing and measurement techniques – Emission and immunity

testing in transverse electromagnetic (TEM) waveguides

Compatibilité électromagnétique (CEM) –

Partie 4-20: Techniques d’essai et de mesure – Essais d’émission et d’immunité

dans les guides d’onde TEM
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.100.10; 33.100.20 ISBN 978-2-8322-1083-0

– 2 – IEC 61000-4-20:2022 © IEC 2022
CONTENTS
FOREWORD . 7
INTRODUCTION . 9
1 Scope . 10
2 Normative references . 11
3 Terms, definitions and abbreviated terms . 11
3.1 Terms and definitions . 11
3.2 Abbreviated terms . 14
4 General . 15
5 TEM waveguide requirements . 15
5.1 General . 15
5.2 General requirements for the use of TEM waveguides . 16
5.2.1 Test volume and maximum EUT size . 16
5.2.2 Validation of usable test volume . 16
5.3 Special requirements and recommendations for certain types of TEM
waveguides . 23
5.3.1 Set-up of open TEM waveguides . 23
5.3.2 Alternative TEM mode verification for a two-port TEM waveguide . 23
5.3.3 TEM mode generation for a four-port TEM waveguide . 23
5.4 Figures for Clause 5 . 24
6 Overview of EUT types . 26
6.1 General . 26
6.2 Small EUT . 26
6.3 Large EUT . 26
7 Laboratory test conditions. 26
7.1 General . 26
7.2 Climatic conditions . 26
7.3 Electromagnetic conditions . 26
8 Evaluation and reporting of test results . 27
Annex A (normative) Emission measurements in TEM waveguides . 28
A.1 Overview. 28
A.2 Test equipment . 28
A.3 Correlating TEM waveguide voltages to electric field strength data . 28
A.3.1 General . 28
A.3.2 Correlation algorithms . 29
A.4 Emission measurement correction factors . 33
A.4.1 Reference emission sources . 33
A.4.2 Arrangement of small EUTs . 34
A.4.3 Calculation of the small EUT correction factor . 34
A.5 Emission measurement procedures in TEM waveguides . 37
A.5.1 EUT types. 37
A.5.2 EUT arrangement . 37
A.6 Test report . 38
A.7 Figures for Annex A . 39
Annex B (normative) Immunity testing in TEM waveguides . 44
B.1 Overview. 44
B.2 Test equipment . 44

B.2.1 General . 44
B.2.2 Description of the test facility . 44
B.3 Field uniformity area calibration . 45
B.4 Test levels . 45
B.5 Test set-up . 45
B.5.1 Arrangement of table-top equipment . 45
B.5.2 Arrangement of floor-standing equipment . 46
B.5.3 Arrangement of wiring . 46
B.6 Test procedures . 46
B.7 Test results and test report . 46
B.8 Figures for Annex B . 47
Annex C (normative) HEMP transient testing in TEM waveguides . 49
C.1 Overview. 49
C.2 Immunity tests . 49
C.2.1 General . 49
C.2.2 Radiated test facilities . 50
C.2.3 Frequency domain spectrum requirements . 51
C.3 Test equipment . 51
C.4 Test set-up . 52
C.5 Test procedure . 52
C.5.1 General . 52
C.5.2 Severity level and test exposures . 53
C.5.3 Test procedure . 53
C.5.4 Test execution . 54
C.5.5 Execution of the radiated immunity test . 54
C.6 Figure for Annex C . 55
Annex D (informative) TEM waveguide characterization . 56
D.1 Overview. 56
D.2 Distinction between wave impedance and characteristic impedance. 56
D.3 TEM wave . 57
D.3.1 General . 57
D.3.2 Free-space TEM mode . 57
D.3.3 Waveguides . 57
D.4 Wave propagation . 58
D.4.1 General . 58
D.4.2 Spherical propagation . 58
D.4.3 Plane wave propagation in free space . 58
D.4.4 Velocity of propagation . 58
D.5 Polarization . 58
D.6 Types of TEM waveguides . 59
D.6.1 General . 59
D.6.2 Open TEM waveguides (striplines, etc.) . 60
D.6.3 Closed TEM waveguides (TEM cells) . 60
D.7 Frequency limitations . 60
D.8 Figures for Annex D . 61
Annex E (informative) Calibration method for E-field probes in TEM waveguides . 69
E.1 Overview. 69
E.2 Probe calibration requirements . 69
E.2.1 General . 69

– 4 – IEC 61000-4-20:2022 © IEC 2022
E.2.2 Calibration frequency range . 69
E.2.3 Calibration volume . 70
E.2.4 Probe dimensions . 70
E.2.5 Perturbations of TEM waveguide fields due to the probe . 70
E.2.6 Frequency steps . 71
E.2.7 Field strength . 71
E.3 Requirements for calibration instrumentation . 71
E.3.1 Specifications of TEM waveguide . 71
E.3.2 Harmonics and spurious signals . 72
E.3.3 Probe fixture . 72
E.3.4 Measuring net power to a transmitting device using directional couplers . 72
E.4 E-field probe calibration . 73
E.4.1 Calibration methods . 73
E.4.2 Calibration procedure using a two-port TEM waveguide . 73
E.4.3 Calibration procedure using one-port TEM waveguide . 74
E.5 Figures for Annex E . 77
Annex F (informative) Instrumentation uncertainty of emission measurement results . 79
F.1 Radiated disturbance measurements using a TEM waveguide . 79
F.1.1 Measurand for radiated disturbance measurements using a TEM
waveguide . 79
F.1.2 Symbols of input quantities common to all disturbance measurements . 79
F.1.3 Symbols of input quantities specific to TEM waveguide measurements . 79
F.2 Input quantities to be considered for radiated disturbance measurements
using a TEM waveguide . 79
F.3 Uncertainty budget and rationale for the input quantities for radiated
disturbance measurements using a TEM waveguide . 80
F.3.1 Uncertainty budget for radiated disturbance measurements using a TEM

waveguide . 80
F.3.2 Rationale for the estimates of input quantities for radiated disturbance
measurements using a TEM waveguide . 81
F.4 Figures for Annex F . 87
Annex G (informative) Measurement uncertainty of immunity testing due to test
instrumentation . 89
G.1 General symbols . 89
G.2 Symbol and definition of the measurand . 89
G.3 Symbols for input quantities . 89
G.4 Example: Uncertainty budget for immunity test . 89
G.5 Rationale for the estimates of input quantities . 90
Annex H (informative) Correlation of emission and immunity limits between EMC test
facilities . 93
H.1 Overview. 93
H.2 Dipole in free space (representing FAR set-up) . 93
H.3 Dipole in half space (representing OATS or SAC set-up). 95
H.4 Dipole in a TEM-mode transmission line . 96
H.5 Dipole in a reverberation chamber . 97
H.6 Correlation . 98
H.7 Example of emission limits . 99
H.8 Figures for Annex H . 100
Annex I (informative) TEM waveguide transient characterization . 103
I.1 Overview. 103

I.2 Test equipment . 103
I.3 Test set-up . 103
I.4 TEM waveguide characterization by correlation . 104
I.5 Quantification of the Pcc . 105
I.6 Performable transient test signals . 105
I.7 Figures for Annex I . 106
Bibliography . 108

Figure 1 – Flowchart of TEM mode and field uniformity verification procedure with the
“constant forward power” method (see 5.2.2.4.1) . 24
Figure 2 – Flowchart of TEM mode and field uniformity verification procedure with the

“constant field strength” method (see 5.2.2.4.2) . 25
Figure A.1 – Routing the exit cable to the corner at the ortho-angle and the lower edge
of the test volume in a TEM waveguide (see A.5.2) . 39
Figure A.2 – Basic ortho-axis EUT positioner or manipulator (see 3.1.13, A.4.2,
A.5.1.2, A.5.2) . 40
Figure A.3 – Die pattern and axis alignment for an EUT [26] (see A.3.2.3.2) . 41
Figure A.4 – Non-redundant twelve-face and axis orientations for a typical EUT [26]
(see A.3.2.3.2) . 42
Figure A.5 – Open-area test site (OATS) emission measurements geometry (see
A.3.2.4) . 43
Figure B.1 – Example of test set-up for single-polarization TEM waveguide
(see Clause B.5) . 47
Figure B.2 – Uniform area calibration points in a TEM waveguide (see Clause B.3) . 48
Figure C.1 – Pulse waveform frequency domain spectral magnitude between 100 kHz

and 300 MHz (see C.2.1) . 55
Figure D.1 – Simple waveguide (no TEM mode) (see D.3.3) . 61
Figure D.2 – Example of waveguides supporting TEM-mode propagation (see D.3.3) . 61
Figure D.3 – E-field polarization vector (see Clause D.5) . 61
Figure D.4 – Simple transmission line model for TEM mode propagation (see D.6.1) . 62
Figure D.5 – One- and two-port TEM waveguide concepts (see D.6.1) . 62
Figure D.6 – Operation of four-port TEM waveguides (see D.6.1) . 62
Figure D.7 – Two-port TEM cell (symmetric septum) (see D.6.1 and D.6.3) . 63
Figure D.8 – One-port TEM cell (asymmetric septum) (see D.6.1 and D.6.3) . 64
Figure D.9 – Stripline (two plates) (see D.6.1 and D.6.2) . 66
Figure D.10 – Stripline (four plates, balanced feed) (see D.6.1) . 67
Figure D.11 – Four-port TEM waveguide (symmetric parallel septa) (see D.6.1 and
D.6.3) . 68
Figure E.1 – Example of test points for calibration volume validation (see E.2.3) . 77
Figure E.2 – Set-up for validation of probe perturbation (see E.2.5) . 77
Figure E.3 – Set-up for measuring net power to a transmitting device (not to scale)
(see E.3.4) . 77
Figure E.4 – Example set-up for E-field probe calibration with two-port TEM waveguide

(see E.4.2) . 78
Figure E.5 – Example set-up for E-field probe calibration with one-port TEM waveguide
and alternative method (see E.4.3.2) . 78
Figure E.6 – Equivalent circuit of monopole antenna and measuring apparatus (see
E.4.3.3) . 78

– 6 – IEC 61000-4-20:2022 © IEC 2022
Figure F.1 – Deviation of the QP detector level indication from the signal level at
receiver input for two cases, a sine-wave signal and an impulsive signal with a pulse
repetition frequency of 100 Hz . 87
Figure F.2 – Deviation of the peak detector level indication from the signal level at
receiver input for two cases, a sine-wave signal and an impulsive signal with a pulse
repetition frequency of 100 Hz . 88
Figure H.1 – Representation of a short centre-fed dipole and a more general source

representing an EUT (see Clause H.2) . 100
Figure H.2 – Vertical source and receiving dipoles located over a perfectly-conducting
ground plane of infinite extent (see Clause H.3) . 100
Figure H.3 – Two types of TEM cells with a vertically polarized dipole source and the
source to receive port geometry defined (see Clause H.4) . 101
Figure H.4 – Reverberation chamber with a source dipole, a stirrer to randomize the

fields, and a general receive antenna (see Clause H.5) . 101
Figure H.5 – TEM waveguide Class A and Class B emission limits correlated from
CISPR 32 [68] (see Clause H.7) . 102
Figure I.1 – Test set-up . 106
Figure I.2 – Signal windowing . 107
Figure I.3 – Example of a heatmap – Pcc for a test point in the uniform area . 107

Table 1 – Values k for expanded uncertainty with normal distribution . 18
Table B.1 – Uniform area calibration points . 45
Table B.2 – Test levels . 45
Table C.1 – Radiated immunity test levels defined for this document . 50
Table E.1 – Calibration frequencies . 71
Table E.2 – Calibration field strength level . 71
Table F.1 – Uncertainty budget for radiated disturbance measurement results using a
TEM waveguide from 30 MHz to 1 000 MHz (example) . 80
Table F.2 – Uncertainty budget for radiated disturbance measurement results using a

TEM waveguide from 1 GHz to 6 GHz (example) . 81
Table F.3 – Values of S for 30 MHz to 1 000 MHz . 83
lim
Table F.4 – Values of S for 1 GHz to 6 GHz . 84
lim
Table G.1 – Example uncertainty budget of the immunity test level . 90
Table H.1 – Summary of the emission correlation parameters . 99

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTROMAGNETIC COMPATIBILITY (EMC) –

Part 4-20: Testing and measurement techniques –
Emission and immunity testing in transverse
electromagnetic (TEM) waveguides

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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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 61000-4-20 has been prepared by subcommittee 77B: High
frequency phenomena, of IEC technical committee 77: Electromagnetic compatibility, in
cooperation with CISPR (International Special Committee on Radio Interference)
subcommittee A: Radio-interference measurements and statistical methods.
It forms Part 4-20 of IEC 61000. It has the status of a basic EMC publication in accordance with
IEC Guide 107.
This third edition cancels and replaces the second edition published in 2010. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) provide information on the testing of large EUTs (including cables);

– 8 – IEC 61000-4-20:2022 © IEC 2022
b) apply the work on measurement uncertainties by adapting the work completed in CISPR and
TC 77 (for emissions and immunity);
c) update the validation procedure for the test volume regarding field uniformity and TEM mode
verification;
d) provide information concerning two-port and four-port TEM waveguides;
e) add a new informative annex (Annex I) dealing with transient TEM waveguide
characterization; and
f) add information dealing with dielectric test stands for EUTs.
The text of this International Standard is based on the following documents:
Draft Report on voting
77B/853/FDIS 77B/855/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/standardsdev/publications.
A list of all parts of the IEC 61000 series, published under the general title Electromagnetic
compatibility (EMC), can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates that it
contains colours which are considered to be useful for the correct understanding of its
contents. Users should therefore print this document using a colour printer.

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,
Technical Specifications or Technical Reports, some of which have already been published as
sections. Others are and will be published with the part number followed by a dash and a second
number identifying the subdivision (example: IEC 61000-6-1).
This part is an International Standard which gives emission, immunity and HEMP and IEMI
transient testing requirements.

– 10 – IEC 61000-4-20:2022 © IEC 2022
ELECTROMAGNETIC COMPATIBILITY (EMC) –

Part 4-20: Testing and measurement techniques –
Emission and immunity testing in transverse
electromagnetic (TEM) waveguides

1 Scope
This part of IEC 61000 focuses on emission and immunity test methods for electrical and
electronic equipment using various types of transverse electromagnetic (TEM) waveguides.
These types include open structures (for example striplines and electromagnetic pulse
simulators) and closed structures (for example TEM cells). These structures can be further
classified as one-port, two-port, or multi-port TEM waveguides. The frequency range depends
on the specific testing requirements and the specific TEM waveguide type.
The object of this document is to describe
– TEM waveguide characteristics, including typical frequency ranges and equipment-under-
test (EUT) size limitations;
– TEM waveguide validation methods for electromagnetic compatibility (EMC) tests;
– the EUT (i.e. EUT cabinet and cabling) definition;
– test set-ups, procedures, and requirements for radiated emission measurements in TEM
waveguides; and
– test set-ups, procedures, and requirements for radiated immunity testing in TEM
waveguides.
NOTE Test methods are defined in this document to measure the effects of electromagnetic radiation on equipment
and the electromagnetic emissions from the equipment concerned. The simulation and measurement of
electromagnetic radiation is not adequately exact for the quantitative determination of effects for all end-use
installations. The test methods defined are structured for a primary objective of establishing adequate reproducibility
of results at various test facilities for qualitative analysis of effects.
This document does not intend to specify the tests to be applied to any particular apparatus or
system(s). The main intention of this document is to provide a general basic reference for all
interested product committees of the IEC. For radiated emission measurements, product
committees select emission limits and measurement methods in consultation with CISPR
standards. For radiated immunity testing, product committees remain responsible for the
appropriate choice of immunity tests and immunity test limits to be applied to equipment within
their scope. This document describes test methods that are separate from those of
IEC 61000‑4‑3 [34].
___________
Numbers in square brackets refer to the Bibliography.
These other distinct test methods may be used when so specified by product committees, in consultation with CISPR
and TC 77.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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) – Part 161: Electromagnetic
compatibility
CISPR 16-1-1, Specification for radio disturbance and immunity measuring apparatus and
methods – Part 1-1: Radio disturbance and immunity measuring apparatus – Measuring
apparatus
CISPR 16-1-4, 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
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-161and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1.1
anechoic material
material that exhibits the property of absorbing, or otherwise reducing, the level of
electromagnetic energy reflected from that material
3.1.2
broadband transmission-line termination
termination which combines a low-frequency discrete-component load, to match the
characteristic impedance of the TEM waveguides (typically 50 Ω), and a volume of high-
frequency anechoic material
3.1.3
characteristic impedance
for any constant phase wave-front, magnitude of the ratio of the voltage between the inner
conductor and the outer conductor to the current on either conductor and which is independent
of the voltage/current magnitudes and depends only on the cross-sectional geometry of the
transmission line
Note 1 to entry: TEM waveguides are typically designed to have a characteristic impedance of 50 Ω. TEM
waveguides with a characteristic impedance of 100 Ω are often used for transient testing.
3.1.4
correlation algorithm
mathematical routine for converting TEM waveguide voltage measurements to open-area test
sites (OATS), semi-anechoic chamber (SAC), or f
...