07-38 - Applied Electromagnetics Group

77B/559/CDV 

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2007-11-02 

Titre du CE/SC: Phénomènes haute fréquence 

IEC 61000-4-6 Ed.2 A3 

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mandatory for P-members) 

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2008-04-04 

TC/SC Title: High frequency phenomena 

Secretary: Jacques DELABALLE 

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DOCUMENTATION. 

Titre : Amendement 3 à la CEI 61000-4-6 

édition 2: Incertitude de mesure 

Title : Amendment 3 to IEC 61000-4-6 Ed. 2: 

Measurement uncertainty 

Note d'introduction 

Introductory note 

The French version will be circulated later 

Copyright © 2007 International Electrotechnical Commission, IEC. All rights reserved. It is 

permitted to download this electronic file, to make a copy and to print out the content for the sole 

purpose of preparing National Committee positions. You may not copy or "mirror" the file or 

printed version of the document, or any part of it, for any other purpose without permission in 

writing from IEC. 

FORM CDV (IEC) 

2005-09-23

61000-4-6A3 Ed.2/CDV © IEC:200X – 2 – 

FOREWORD 

This amendment has been prepared by subcommittee 77B: High frequency phenomena, of 

IEC technical committee 77: Electromagnetic compatibility. 

The text of this amendment is based on the following documents: 

FDIS 

77B/XX/FDIS 

Report on voting 

77B/XX/RVD 

Full information on the voting for the approval of this amendment can be found in the report 

on voting indicated in the above table. 

The committee has decided that the contents of this amendment and the base publication will 

remain unchanged until the maintenance result date 1) 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• withdrawn, 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. 

_____________ 

————————— 

1) The National Committees are requested to note that for this publication the maintenance result date is 2010.

61000-4-6A3 Ed.2/CDV © IEC:200X – 3 – 

Annex G 

(informative) 

Measurement Uncertainty of Test Instrumentation 

G.1 Introduction 

This annex gives information related to Measurement Uncertainty (MU) according to the 

particular needs of the test method contained in the main body of the standard. Further 

information can be found in [1]. 

This document focuses on the uncertainties for level setting. Other parameters of the 

disturbance quantity may be of equal importance and should also be considered by the test 

laboratory. The methodology shown in this annex is considered to be applicable to all 

parameters of the disturbance quantity. 

G.2 Uncertainty budgets for test methods 

G.2.1 

Definition of the measurand 

The measurand is the open circuit voltage U 0 , derived from the measurement of the output of 

the coupling device into a well defined 150 Ω voltage divider. 

G.2.2 

MU contributors of the measurand 

The following influence diagrams (Figures G.1 to G.4) give examples of influences upon the 

test method. It should be understood that the diagrams are not exhaustive. The most 

important contributors from the influence diagrams have been selected for the uncertainty 

budget Tables G.1, G.3, G.4 and G.5. At least these contributors listed in the Tables G.1, G.3, 

G.4 and G.5 shall be used for the uncertainty budgets in order to get comparable budgets for 

different test sites or laboratories. It is noted that a laboratory may include additional 

contributors (e.g. Type A) in the calculation of the MU, based on its particular circumstances. 

Level meter 

Test generator 

level 


linearity 


level drift 

Mismatch 

level meter/CDN 

Set-up for level 

setting 

Uncertainty in 

level setting 

SW levelling 

precision 

Power amp 

harmonics 

Power amp 

Compression 

CDN cal data 

Mismatch 

Test generator / 

CDN 

150 Ω to 50 Ω adapter 

Figure G.1: Example of influences upon the test method using CDN

61000-4-6A3 Ed.2/CDV © IEC:200X – 4 – 

Level meter 

Test 

generator level 


linearity 


level drift 

Mismatch 

level meter/clamp 

150 Ω to 50 Ω adapter 


level setting 

SW levelling 

precision 

Power amp 

harmonics 

Power amp 

compression 

Monitoring system 

(current probe and 

meter) 

EM clamp 

calibration 

Mismatch Test generator / 

clamp 

Figure G.2: Example of influences upon the test method using EM clamp 

Level meter 


level 


linearity 


level drift 

150 Ω to 50 Ω 

adapter 

Mismatch 

Level meter / 

clamp 


level setting 

Power amp 

compression 

SW levelling 

precision 

Power amp 

harmonics 

Monitoring system 

(current probe, meter) 

Clamp 

calibration 

Mismatch Test generator / 

clamp 

Figure G.3: Example of influences upon the test method using Current clamp 

Level meter 

Test 

generator level 


linearity 


level drift 

Mismatch 

Test generator / 

injection 

150 Ω to 50 Ω 

adapter 


level setting 

SW levelling 

precision 

Power amp 

harmonics 

Power amp 

compression 

Direct injection 

calibration 

Decoupling 

devices 

Figure G.4: Example of influences upon the test method using direct injection

61000-4-6A3 Ed.2/CDV © IEC:200X – 5 – 

G.2.3 

Calculation examples for expanded uncertainty 

It must be recognized that the contributions which apply for calibration and for test may not be 

the same. This leads to (slightly) different uncertainty budgets for each process. 

The Tables G.1, G.3, G.4 and G.5 give examples of an uncertainty budget for level setting. 

Each uncertainty budget consists of 2 parts, the uncertainty for calibration and the uncertainty 

for test. 

Table G.1a: CDN calibration process 

Symbol Uncertainty Source u(x i ) Unit Distribution Divisor c i u i (y) Unit u i (y) 2 

RCAL 150 to 50 Ohm adapter, deviation 0.3 dB rect 1.73 1 0.17 dB 0.03 

150 to 50 Ohm adapter, calib. 0.2 dB normal k=2 2 1 0.10 dB 0.01 

SETUP Set-up for level setting 0.35 dB normal k=1 1 1 0.35 dB 0.12 

CDN CDN impedance 0.6 dB rect 1.73 1 0.35 dB 0.12 

LMc Level meter 0.5 dB rect 1.73 1 0.29 dB 0.08 

SWc SW levelling precision 0.3 dB rect 1.73 1 0.17 dB 0.03 

LMCc (a,b) Level meter in control loop 0 dB rect 1.73 1 0.00 dB 0.00 

TGc (a,b) Test generator 0 dB rect 1.73 1 0.00 dB 0.00 

MTc (c) Mismatch Test generator/CDN 0 dB U-shaped 1.41 1 0.00 dB 0.00 

ML Mismatch Level meter/CDN -0.5 dB U-shaped 1.41 1 -0.35 dB 0.13 

Σ u i (y) 2 0.52 

Combined uncertainty u(y)= √ Σ u i (y) 2 0.72 

Expanded Uncertainty (CAL ) U=u(y).k , k = 2 

1.45 dB 

Table G.1b: CDN test process 


CAL Calibration 1.45 dB normal k=2 2 1 0.72 dB 0.52 

LMCt (a,b) Level meter in control loop 0.3 dB rect 1.73 1 0.17 dB 0.03 

TGt (a,b) Test generator 0 dB rect 1.73 1 0.00 dB 0.00 

MTt (c) Mismatch Test generator/CDN 0 dB U-shaped 1.41 1 0.00 dB 0.00 

SWt SW levelling precision 0.3 dB rect 1.73 1 0.17 dB 0.03 

Σ u i (y) 2 0.58 


Expanded uncertainty U=u(y).k, k = 2 

1.53 dB 

Notes: 

(a) Either LMC or TG contributions enter into the table for calibration and/or test, depending on whether a control 

loop for the signal generator and amplifier output level is used or not. A more detailed analysis of the TG 

contribution may be needed in case of not using a control loop, see explanation of terms. 

(b) If the same equipment is used for calibration and testing then only the contributions of repeatability and 

linearity enter into the table for the test process. The contribution for the calibration can be neglected. 

(c) If the same circuit is used for calibration and testing then these contributions do not enter into the table. 

Explanation of terms: 

RCAL - is the uncertainty of the 150 Ω to 50 Ω adapter. This contribution can normally be 

obtained from the calibration report. Alternatively the insertion loss can be measured using a 

network analyzer (see Fig. 7c of the main document). The maximum deviation from the 

specified loss (9,5 dB) and its calibration uncertainty should be included in the table. 0,5 dB 

should be used if the calibration certificate states only the compliance to the tolerance. 

Note 1: Deviations may be corrected in the software. In this case the maximum deviation can be reduced to the 

interpolation uncertainty and calibration uncertainty. 

Note 2: The impedance of the 150 Ω to 50 Ω adapter can also be measured directly, e.g. using a network analyzer 

or taken from the calibration certificate. In this case the deviation (in dB) from 100 Ω and the calibration uncertainty 

should be inserted in the table.

61000-4-6A3 Ed.2/CDV © IEC:200X – 6 – 

SETUP – is a combination of uncertainties introduced by the setup for level setting, i.e. cal 

fixture, the connection between the CDN and the CDN adapter and the ground plane impacts, 

e.g. contact to the ground plane. This contribution can be derived from reproducibility tests 

with changing conditions or estimated based on experience as done in the example. 

CDN – is the influence of the CDN impedance on the test level. This contribution does not 

cover a possible variation of the EUT impedance itself, only the contribution of the test 

instrumentation. 

Deviations of the CDN impedance result in an increased or decreased loop impedance of 

nominal 300 Ω. Thus a different signal level is established during the calibration process. If 

the EUT is 150 Ω the influence of the CDN impedance cannot be seen in the voltage at the 

EUT terminals. If the EUT impedance is high (open circuit as worst case) the EUT will be 

tested with a maximum voltage of U’ 0 . Table G.1a contains typical values for this contribution. 

The CDN impedance should be determined by measurements. The worst case situations are 

shown in Table G.2. 

U 

0 

Zloop 

= ⋅U 

300 Ω 

′ (G.1) 

0 

U′ 

⎛ U′ 

= 20 ⋅lg 

0 

⎜ 

⎝ U 

⎞ ⎛Z 

⎟ = 20 ⋅lg⎜ 

⎠ ⎝ 

⎞ 

300 Ω 

⎟ 

⎠ 

δ 

loop 

0, dB 

(G.2) 

0 

Table G.2: Uncertainty in dependence of CDN impedance variations 

Impedance of 

the CDN 

Ω 

Loop 

impedance 

Z loop 

Ω 

δU 0,dB 

dB 

150 300 0,0 

170 320 0,6 

130 280 -0,6 

210 360 1,6 

105 255 -1,4 

LM c – is the uncertainty of the level meter, i.e. voltmeter or power meter used for 

measurement of the level at the output of the CDN. It is taken from the manufacturer’s 

specifications in the example but could be determined from other sources as well. 

SW c – is the uncertainty derived from the discrete level step size of the signal generator and 

software windows for level setting during the calibration process. The software window can 

usually be adjusted by the test lab. 

LMC c – is the uncertainty of the level meter, i.e. voltmeter or power meter used for control 

loop for the signal generator and amplifier output level. It can be taken from the 

manufacturer’s specifications or determined from other sources. 

TG c – is the uncertainty of the test generator including frequency generator, power amplifier 

and attenuator. It can be taken from the manufacturer’s specifications or determined from 

other sources.

61000-4-6A3 Ed.2/CDV © IEC:200X – 7 – 

Note: The uncertainty of the individual components of the test generator (e.g. signal generator, power amplifier 

stability, power amplifier rapid gain variation, attenuator etc.) may have to be assessed separately, especially in 

case of not using a control loop in the test setup. 

MT c – is a combination of the mismatches between amplifier, attenuator and CDN. 

ML – is the mismatch between the CDN and the level meter. 

CAL – is the expanded uncertainty of the test voltage level. 

LMC t – is the uncertainty of the level meter, e.g. voltmeter, used at the output of the power 

amplifier taken from manufacturer specification. Alternatively a power meter can be used in 

order to obtain a lower uncertainty. 

TG t – is the uncertainty of the test generator including frequency generator, power amplifier 

and attenuator. It can be taken from the manufacturer’s specifications or determined from 

other sources. 

Note: The uncertainty of the individual components of the test generator (e.g. signal generator, power amplifier 

stability, power amplifier rapid gain variation, attenuator etc.) may have to be assessed separately, especially in 

case of not using a control loop in the test set-up. 

MT t – is a combination of the mismatches between amplifier, attenuator and CDN. This 

contribution can be neglected if the same setup, i.e. attenuator and cables, is used for 

calibration and test. 

SW t – is the uncertainty derived from the discrete level step size of the signal generator and 

software windows for level setting during the test process. The software window can usually 

be adjusted by the test lab.

61000-4-6A3 Ed.2/CDV © IEC:200X – 8 – 

Table G.3a: EM clamp calibration process 





EM EM clamp 1 dB normal k=2 2 1 0.50 dB 0.25 





MTc (c) Mismatch Test generator/clamp 0 dB U-shaped 1.41 1 0.00 dB 0.00 

ML Mismatch Level meter/clamp -0.5 dB U-shaped 1.41 1 -0.35 dB 0.13 

Σ u i (y) 2 0.65 



1.61 dB 

Table G.3b: EM clamp test process 





MTt (c) Mismatch Test generator/clamp 0 dB U-shaped 1.41 1 0.00 dB 0.00 


AETERM AE termination 2.5 dB rect 1.73 1 1.45 dB 2.09 

Σ u i (y) 2 2.80 

Notes: 



3.35 dB 








Several items apply in principle as for the previous example (CDN method). These items are 

not explained here, please refer to the previous example. 

Note Uncertainty related to Clause 7.4 where monitoring probe is used and current limitation is applied is not 

considered in this annex. In this case the value of U 0 is no longer the same that was determined in the level setting 

procedure, but it is reduced to an unknown value. Therefore no uncertainty can be assigned to U 0 in this case. 

EM – is the uncertainty of the EM clamp characterization, mostly due to the deviation of the 

output impedance from 150 Ω. 

AETERM – is the effect of the AE impedance, which should be maintained at 150 Ω. 

Deviations have significant influence especially in the lower frequency range (below 10 MHz), 

where the directivity of the EM clamp is weak. This is assumed for the value given in the 

table. A lower value may be used for frequencies above 10 MHz. 

This contribution can be investigated experimentally using a network analyzer. The coupling 

factor of the clamp can be measured for a 150 Ω AE impedance and compared to different AE 

impedances.

61000-4-6A3 Ed.2/CDV © IEC:200X – 9 – 

Table G.4a: Current clamp calibration process 




JIG Calibration jig 0.5 dB normal k=1 1 1 0.50 dB 0.25 





MTc (c) Mismatch Test generator/clamp 0 dB U-shaped 1.41 1 0.00 dB 0.00 

ML Mismatch Level meter/clamp -0.5 dB U-shaped 1.41 1 -0.35 dB 0.13 

Σ u i (y) 2 0.53 



1.46 dB 

Table G.4b: Current clamp test process 







AETERM AE termination 2.5 dB rect 1.73 1 1.45 dB 2.09 

Σ u i (y) 2 2.68 



3.27 dB 

Notes: 








Several items apply in principle as for one of the previous examples (e.g. CDN method). 

These items are not explained here, please refer to one of the previous examples. 

Note Uncertainty related to Clause 7.4 where monitoring probe is used and current limitation is applied is not 

considered in this annex. In this case the value of U 0 is no longer the same that was determined in the level setting 

procedure, but it is reduced to an unknown value. Therefore no uncertainty can be assigned to U 0 in this case. 

JIG – is a combination of uncertainties introduced by the test jig. This contribution can be 

derived from reproducibility tests with changing conditions or estimated based on experience 

as done in the example.

61000-4-6A3 Ed.2/CDV © IEC:200X – 10 – 

Table G.5a: Direct injection calibration process 









MTc (c) Mismatch Test generator/CDN 0 dB U-shaped 1.41 1 0.00 dB 0.00 

ML Mismatch Level meter/CDN -0.5 dB U-shaped 1.41 1 -0.35 dB 0.13 

Σ u i (y) 2 0.53 



1.46 dB 

Table G.5b: Direct injection test process 







DD Decoupling devices 2.3 dB rect 1.73 1 1.33 dB 1.77 

Σ u i (y) 2 2.36 

Notes: 



3.07 dB 








Several items apply in principle as for one of the previous examples (e.g. CDN method). 

These items are not explained here, please refer to one of the previous examples. 

DD – is a combined uncertainty of the decoupling devices and the AE termination. Good 

decoupling gives less effect of the AE termination, poor decoupling gives a strong effect. This 

contribution can be calculated from the impedance of the decoupling element. 

G.3 Application 

The calculated MU number (expanded uncertainty) should be used as a method of evaluating 

the quality of a lab’s test process. It is not intended that the result of this calculation be used 

for adjusting the test level that is applied to EUTs during the test process. 

G.4 Bibliography 

[1] 77/349/INF, General information on measurement uncertainty of test 

instrumentation for conducted and radiated RF immunity tests

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