en 55016-4-2 2005

SVENSK STANDARD SS-EN 55016-4-2

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ICS 33.100.10; 33.100.20

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EMC –Utrustning och metoder för mätning av radiostörningar och immunitet –Del 4-2: Onogrannhet vid EMC-mätningar Specification for radio disturbance and immunity measuring apparatus and methods – Part 4-2: Uncertainties, statistics and limit modelling – Uncertainty in EMC measurements

Som svensk standard gäller europastandarden EN 55016-4-2:2004. Den svenska standarden innehåller den

officiella engelska språkversionen av EN 55016-4-2:2004.

Nationellt förord

Europastandarden EN 55016-4-2:2004

består av:

– europastandardens ikraftsättningsdokument, utarbetat inom CENELEC

– CISPR 16-4-2, First edition, 2003 - Specification for radio disturbance and immunity measuring

apparatus and methods - Part 4-2: Uncertainties, statistics and

limit modelling - Uncertainty in EMC measurements

utarbetat inom International Electrotechnical Commission, IEC.

EUROPEAN STANDARD EN 55016-4-2

NORME EUROPÉENNE

EUROPÄISCHE NORM October 2004

CENELECEuropean Committee for Electrotechnical Standardization

Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2004 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 55016-4-2:2004 E

ICS 33.100.10; 33.100.20

English version

Specification for radio disturbance and immunity measuring apparatus and methods

Part 4-2: Uncertainties, statistics and limit modelling – Uncertainty in EMC measurements

(CISPR 16-4-2:2003)

Spécifications des méthodes et des appareils de mesure des perturbations radioélectriques et de l'immunité aux perturbations radioélectriques Partie 4-2: Incertitudes, statistiques et modélisation des limites – Incertitudes de mesure CEM (CISPR 16-4-2:2003)

Anforderungen an Geräte und Einrichtungen sowie Festlegung der Verfahren zur Messung der hochfrequenten Störaussendung (Funkstörungen) und Störfestigkeit Teil 4-2: Unsicherheiten, Statistik und Modelle zur Ableitung von Grenzwerten (Störmodell) – Unsicherheit bei EMV-Messungen (CISPR 16-4-2:2003)

This European Standard was approved by CENELEC on 2004-09-01. 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, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

EN 55016-4-2:2004 - 2 -

Foreword

The text of the International Standard CISPR 16-4-2:2003, prepared by CISPR SC A, Radio-interference measurements and statistical methods, was submitted to the formal vote and was approved by CENELEC as EN 55016-4-2 on 2004-09-01 without any modification.

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) 2005-09-01

– latest date by which the national standards conflicting with the EN have to be withdrawn (dow) 2007-09-01

Annex ZA has been added by CENELEC.

__________

Endorsement notice

The text of the International Standard CISPR 16-4-2:2003 was approved by CENELEC as a European Standard without any modification.

__________

- 3 - EN 55016-4-2:2004

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 Series Specification for radio disturbance and immunity measuring apparatus and methods Part 1: Radio disturbance and immunity measuring apparatus

EN 55016-1 Series

CISPR 16-2 Series Part 2: Methods of measurement of disturbances and immunity

EN 55016-2 Series

CISPR/TR 16-3 - 1) Part 3: CISPR technical reports - -

CISPR/TR 16-4-1 - 1) Part 4-1: Uncertainties, statistics and limit modeling - Uncertainties in standardized EMC tests

- -

CISPR/TR 16-4-3 - 1) Part 4-3: Uncertainties, statistics and limit modelling - Statistical considerations in the determination of EMC compliance of mass-produced products

- -

CISPR/TR 16-4-4 - 1) Part 4-4: Uncertainties, statistics and limit modeling - Statistics of complaints and a model for the calculation of limits

- -

1)Undated reference.

CISPR 16-4-2 IEC:2003 – 3 –

CONTENTS

INTRODUCTION.....................................................................................................................7

TABLE RECAPITULATING CROSS-REFERENCES ................................................................9

1 Scope............................................................................................................................. 11

2 Normative references ..................................................................................................... 11

3 Definitions and symbols.................................................................................................. 13

3.1 General symbols ................................................................................................... 13

3.2 Measurands .......................................................................................................... 13

3.3 Input quantities...................................................................................................... 13

4 Measurement instrumentation uncertainty ...................................................................... 15

4.1 Overview ............................................................................................................... 15

4.2 Quantities to be considered for conducted disturbance measurements at a mains port ............................................................................................................. 17

4.3 Quantities to be considered for disturbance power measurements......................... 17

4.4 Quantities to be considered for radiated disturbance measurements of electric field strength on an open area test site or alternative test site ................... 17

Annex A (informative) Basis for Ucispr values in Table 1........................................................ 21

Bibliography.......................................................................................................................... 43

CISPR 16-4-2 IEC:2003 – 7 –

INTRODUCTION

CISPR 16-1, CISPR 16-2, CISPR 16-3 and CISPR 16-4 have been reorganised into 14 parts, to accommodate growth and easier maintenance. The new parts have also been renumbered. See the list given below.

Statistical considerations in the determination of EMC compliance of mass- produced products

Statistics of complaints and a model for the calculation of limits

CISPR 16-1-3 Ancillary equipment – Disturbance power

Ancillary equipment – Conducted disturbances CISPR 16-1-2

CISPR 16-4-2

Antenna calibration test sites for 30 MHz to 1 000 MHz

Old CISPR 16 publications

Radio disturbance and immunity measuring apparatus

Measuring apparatus

CISPR 16-2-1

New CISPR 16 publications

CISPR 16-1

CISPR 16-1-5

Conducted disturbance measurements

CISPR 16-2-2 Measurement of disturbance power

CISPR 16-2-3 Radiated disturbance measurements CISPR 16-2

Methods of measurement of disturbances and immunity

CISPR 16-2-4 Immunity measurements

CISPR 16-3 CISPR technical reports

CISPR 16-4-1 Uncertainties in standardised EMC tests

Measurement instrumentation uncertainty CISPR 16-3Reports and recommendations of CISPR

CISPR 16-4-3

CISPR 16-4 Uncertainty in EMC measurements

CISPR 16-4-4

CISPR 16-1-1

CISPR 16-1-4 Ancillary equipment – Radiated disturbances

More specific information on the relation between the ‘old’ CISPR 16-4 and the present ‘new’ CISPR 16-4-2 is given in the table after this introduction (TABLE RECAPITULATING CROSS REFERENCES).

Measurement instrumentation specifications are given in five new parts of CISPR 16-1, while the methods of measurement are covered now in four new parts of CISPR 16-2. Various reports with further information and background on CISPR and radio disturbances in general are given in CISPR 16-3. CISPR 16-4 contains information related to uncertainties, statistics and limit modelling.

CISPR 16-4 consists of the following parts, under the general title Specification for radio disturbance and immunity measuring apparatus and methods - Uncertainties, statistics and limit modelling:

Part 4-1: Uncertainties in standardised EMC tests,

Part 4-2: Uncertainty in EMC measurements,

Part 4-3: Statistical considerations in the determination of EMC compliance of mass-produced products,

Part 4-4: Statistics of complaints and a model for the calculation of limits.

CISPR 16-4-2 IEC:2003 – 9 –

TABLE RECAPITULATING CROSS-REFERENCES

First edition of CISPR 16-4 First edition of CISPR 16-4-2 Clauses Clauses

1 1 2 2 3 3 4 4

Annex Annex

A A

CISPR 16-4-2 IEC:2003 – 11 –

SPECIFICATION FOR RADIO DISTURBANCE AND IMMUNITY MEASURING APPARATUS AND METHODS –

Part 4-2: Uncertainties, statistics and limit modelling – Uncertainty in EMC measurements

1 Scope

This part of CISPR 16 is designated a basic standard, which specifies the manner in which measurement uncertainty is to be taken in to account in determining compliance with CISPR limits. The material is also relevant to any EMC test when interpretation of the results and conclusions reached will be impacted by the uncertainty of the instrumentation used during the testing. Annex A contains the background material used in providing the amount of measurement uncertainty found in generating the CISPR values shown in Clause 4 and hence provides valuable background material for those needing both initial and further information on measurement uncertainty and how to take into account individual uncertainties in the measurement chain. The annex however is not intended to be a tutorial of user manual or to be copied when making uncertainty calculations. For that, the references shown in the bibliography should be used.

Measurement instrumentation specifications are given in CISPR 16-1, while the methods of measurement are covered in CISPR 16-2. Further information and background on CISPR and radio disturbances is given in CISPR 16-3. The other parts of CISPR 16-4 contain further information on uncertainties in general, statistics and limit modelling.

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 (all parts), Specification for radio disturbance and immunity measuring apparatus and methods – Radio disturbance and immunity measuring apparatus

CISPR 16-2 (all parts), Specification for radio disturbance and immunity measuring apparatus and methods – Methods of measurement of disturbances and immunity

CISPR 16-3, Specification for radio disturbance and immunity measuring apparatus and methods – Part 3: CISPR technical reports

CISPR 16-4-1, Specification for radio disturbance and immunity measuring apparatus and methods – Part 4-1: Uncertainties, statistics and limit modelling - Uncertainties in standardised EMC tests

CISPR 16-4-3, Specification for radio disturbance and immunity measuring apparatus and methods – Part 4-3: Uncertainties, statistics and limit modelling - Statistical considerations in the determination of EMC compliance of mass-produced products

CISPR 16-4-2 IEC:2003 – 13 –

CISPR 16-4-4, Specification for radio disturbance and immunity measuring apparatus and methods – Part 4-4: Uncertainties, statistics and limit modelling – A model for the calculation of limits

3 Definitions and symbols

For the purpose of this part of CISPR 16, the following symbols apply.

NOTE General uncertainty terms and definitions used in uncertainty are contained in bibliography reference [2]. General definitions are contained in bibliography reference [1]. These definitions will not be repeated here.

3.1 General symbols

Xi input quantity

xi estimate of Xi

u(xi) standard uncertainty of xi

ci sensitivity coefficient

y result of a measurement, (the estimate of the measurand), corrected for all recognised significant systematic effects

uc(y) (combined) standard uncertainty of y

k coverage factor

U expanded uncertainty of y

3.2 Measurands

V Voltage, in dB( V)

P Disturbance power, in dB(pW)

E Electric field strength, in dB( V/m)

3.3 Input quantities

Vr Receiver voltage reading, in dB( V)

Lc Attenuation of the connection between the receiver and the artificial mains network, absorbing clamp or antenna, in dB

Lamn Voltage division factor of the AMN, in dB

Lac Insertion loss of the absorbing clamp, in dB

AF Antenna factor, in dB(/m)

Vsw Correction for receiver sine wave voltage inaccuracy, in dB

Vpa Correction for imperfect receiver pulse amplitude response, in dB

Vpr Correction for imperfect receiver pulse repetition rate response, in dB

Vnf Correction for the effect of the receiver noise floor, in dB

M Correction for the error caused by mismatch, in dB

MD Correction for the error caused by mains disturbances, in dB

Z Correction for imperfect AMN impedance, in dB

E Correction for the effect of the environment, in dB

AFf Correction for antenna factor interpolation error, in dB

CISPR 16-4-2 IEC:2003 – 15 –

AFh Correction for the difference between the antenna factor variation with height, and the variation with height of the antenna factor of a reference dipole, in dB

Adir Correction for antenna directivity, in dB

Aph Correction for antenna phase centre location, in dB

Acp Correction for antenna cross-polarisation response, in dB

Abal Correction for antenna unbalance, in dB

SA Correction for imperfect site attenuation, in dB

d Correction for imperfect antenna distance, in dB

h Correction for imperfect table height above ground plane, in dB

4 Measurement instrumentation uncertainty

4.1 Overview

Measurement instrumentation uncertainty shall be taken into account when determining compliance or non-compliance with a disturbance limit.

The measurement instrumentation uncertainty for a test laboratory shall be evaluated for those measurements addressed in the following subclauses, taking into consideration each of the quantities listed there. The standard uncertainty u(xi) in decibels and the sensitivity coefficient ci shall be evaluated for the estimate xi of each quantity. The combined standard uncertainty uc(y) of the estimate y of the measurand shall be calculated as

i

ii xucyu )()( 22c

The expanded measurement instrumentation uncertainty Ulab for a test laboratory shall be calculated as

)(2 clab yuU

and shall be stated in the test report.

NOTE 1 The coverage factor k = 2 yields approximately a 95 % level of confidence for the near-normal distribution typical of most measurement results.

Compliance or non-compliance with a disturbance limit shall be determined in the following manner.

If Ulab is less than or equal to Ucispr in Table 1, then:

compliance is deemed to occur if no measured disturbance exceeds the disturbance limit;

non-compliance is deemed to occur if any measured disturbance exceeds the disturbance limit.

NOTE Ucispr resembles a value of measurement uncertainty for a specific test, which was determined by considering uncertainties associated with the quantities listed in 4.2.

If Ulab is greater than Ucispr in Table 1, then:

compliance is deemed to occur if no measured disturbance, increased by (Ulab – Ucispr),exceeds the disturbance limit;

non-compliance is deemed to occur if any measured disturbance, increased by (Ulab – Ucispr), exceeds the disturbance limit.

CISPR 16-4-2 IEC:2003 – 17 –

Table 1 – Values of Ucispr

Measurement Ucispr

(9 kHz – 150 kHz) 4,0 dB Conducted disturbance (mains port)

(150 kHz – 30 MHz) 3,6 dB

Disturbance power (30 MHz – 300 MHz) 4,5 dB

Radiated disturbance (electric field strength on an open area test site or alternative test site)

(30 MHz – 1 000 MHz) 5,2 dB

Other Under

consideration

NOTE 2 The values of Ucispr in Table 1 are based on the expanded uncertainties in Annex A, which were evaluated by considering uncertainties associated with the quantities listed below.

Nothing in this clause removes the requirement for measuring apparatus to comply with specifications in CISPR 16-1.

4.2 Quantities to be considered for conducted disturbance measurements at a mains port

– Receiver reading

– Attenuation of the connection between artificial mains network and receiver

– Artificial mains network voltage division factor

– Receiver sine-wave voltage accuracy

– Receiver pulse amplitude response

– Receiver pulse response variation with repetition frequency

– Receiver noise floor

– Mismatch effects between artificial mains network receiver port and receiver

– Artificial mains network impedance

4.3 Quantities to be considered for disturbance power measurements


– Attenuation of the connection between absorbing clamp and receiver

– Absorbing clamp insertion loss





– Mismatch effects between absorbing clamp receiver port and receiver

– Effect of mains disturbances

– Effect of environment

4.4 Quantities to be considered for radiated disturbance measurements of electric field strength on an open area test site or alternative test site


– Attenuation of the connection between antenna and receiver

– Antenna factor


CISPR 16-4-2 IEC:2003 – 19 –




– Mismatch effects between antenna port and receiver

– Antenna factor frequency interpolation

– Antenna factor variation with height

– Antenna directivity

– Antenna phase centre

– Antenna cross-polarisation response

– Antenna balance

– Test site

– Separation between equipment under test and measurement antenna

– Height of table supporting the equipment under test

CISPR 16-4-2 IEC:2003 – 21 –

Annex A (informative)

Basis for Ucispr values in Table 1

A.1 General

The following clauses outline the approach used to determine Ucispr for the various measurements. The main uncertainty components for each measurement are identified and an estimate of their magnitude provided. All assumptions made are documented in Clause A.5 and referenced as notes in the actual uncertainty estimate.

Definitions of measurement uncertainty terms, and information on the evaluation and expression of the uncertainty of measurement are available in references [1] to [4] of the bibliography.

A.2 Conducted disturbance measurements at a mains port

The measurand V is calculated as:

ZV nfprpasw

amncr

MVVV

LLVV

Table A.1 Conducted disturbances from 9 kHz to 150 kHz

using a 50 /50 H + 5 AMN

Input quantity Xi Uncertainty of xi u(xi) ci ci u(xi)

dB Probability distribution

function

dB dB

Receiver reading 1) a Vr ±0,1 k = 1 0,10 1 0,10

Attenuation: AMN-receiver 2) Lc ±0,1 k = 2 0,05 1 0,05

AMN voltage division factor 3) Lamn 0,2 k = 2 0,10 1 0,10

Receiver corrections:

Sine wave voltage 4) Vsw 1,0 k = 2 0,50 1 0,50

Pulse amplitude response 5) Vpa 1,5 Rectangular 0,87 1 0,87

Pulse repetition rate response 5) Vpr 1,5 Rectangular 0,87 1 0,87

Noise floor proximity 6) Vnf 0,0 0,00 1 0,00

Mismatch: AMN-receiver 7) M +0,7/–0,8 U-shaped 0,53 1 0,53

AMN impedance 8) Z +3,1/–3,6 Triangular 1,37 1 1,37

a For numbered comments, see article A.5.

Hence: 2 uc(V) = 3,97 dB

CISPR 16-4-2 IEC:2003 – 23 –

Table A.2 Conducted disturbances from 150 kHz to 30 MHz

using a 50 /50 H AMN



function

dB dB


Attenuation: AMN-receiver 2) Lc ±0,1 k = 2 0,05 1 0,05

AMN voltage division factor 3) Lamn 0,2 k = 2 0,10 1 0,10






Mismatch: AMN-receiver 7) M +0,7/–0,8 U-shaped 0,53 1 0,53

AMN impedance 8) Z +2,6/–2,7 Triangular 1,08 1 1,08


Hence: 2 uc(V) = 3,60 dB

A.3 Disturbance power measurements

The measurand P is calculated as:

EMDMVVVV

LLVP

nfprpasw

10accr (50)log10

Table A.3 Disturbance power from 30 MHz to 300 MHz



function

dB dB


Attenuation: Absorbing clamp-receiver 2) Lc ±0,1 k = 2 0,05 1 0,05

Absorbing clamp insertion loss 9) Lac 3,0 k = 2 1,50 1 1,50






Mismatch: Absorbing clamp-receiver 7) M +0,7/–0,8 U-shaped 0,53 1 0,53

Effect of mains disturbances 10) MD 0,0 0,00 1 0,00

Effect of environment 11) E 0,8 k = 1 0,80 1 0,80


Hence: 2 uc(P) = 4,45 dB

CISPR 16-4-2 IEC:2003 – 25 –

A.4 Radiated disturbance measurements of electric field strength on an open area test site or alternative test site

The measurand E is calculated as:

hdSAAAAAAFAFMVVVV

AFLVE

balcpphdirhfnfprpasw

cr

Table A.4 Horizontally polarised radiated disturbances from 30 MHz to 200 MHz using a biconical antenna at a distance of 3 m, 10 m, or 30 m



function

dB dB


Attenuation: antenna-receiver 2) Lc ±0,1 k = 2 0,05 1 0,05

Biconical antenna factor 12) AF 2,0 k = 2 1,00 1 1,00





Noise floor proximity 6) Vnf 0,5 k = 2 0,25 1 0,25

Mismatch: antenna-receiver 7) M +0,9/–1,0 U-shaped 0,67 1 0,67

Biconical antenna corrections:

AF frequency interpolation 13) AFf ±0,3 Rectangular 0,17 1 0,17

AF height deviations 14) AFh ±0,5 Rectangular 0,29 1 0,29

Directivity difference 15) at 3 m Adir 0,0 0,00 1 0,00

or 10 m Adir 0,0 0,00 1 0,00

or 30 m Adir 0,0 0,00 1 0,00

Phase centre location 16) at 3 m Aph 0,0 0,00 1 0,00

or 10 m Aph 0,0 0,00 1 0,00

or 30 m Aph 0,0 0,00 1 0,00

Cross-polarisation 17) Acp 0,0 0,00 1 0,00

Balance 18) Abal ±0,3 Rectangular 0,17 1 0,17

Site corrections:

Site imperfections 19) SA ±4,0 Triangular 1,63 1 1,63

Separation distance 20)

at 3 m d ±0,3 Rectangular 0,17 1 0,17

or 10 m d ±0,1 Rectangular 0,06 1 0,06

or 30 m d ±0,0 0,00 1 0,00

Table height 21)

at 3 m h ±0,1 k = 2 0,05 1 0,05

or 10 m h ±0,1 k = 2 0,05 1 0,05

or 30 m h ±0,1 k = 2 0,05 1 0,05


Hence: 2 uc(E) = 4,95 dB at a separation of 3 m 4,94 dB at a separation of 10 m 4,94 dB at a separation of 30 m

CISPR 16-4-2 IEC:2003 – 27 –

Table A.5 Vertically polarised radiated disturbances from 30 MHz to 200 MHz using a biconical antenna at a distance of 3 m, 10 m, or 30 m



function

dB dB



Biconical antenna factor 12) AF 2,0 k = 2 1,00 1 1,00





Noise floor proximity 6) Vnf 0,5 k = 2 0,25 1 0,25


Biconical antenna corrections:



Directivity difference 15) at 3 m Adir +1,0/–0,0 Rectangular 0,29 1 0,29

or 10 m Adir +1,0/–0,0 Rectangular 0,29 1 0,29


Phase centre location 16) at 3 m Aph 0,0 0,00 1 0,00

or 10 m Aph 0,0 0,00 1 0,00

or 30 m Aph 0,0 0,00 1 0,00

Cross-polarisation 17) Acp 0,0 0,00 1 0,00

Balance 18) Abal ±0,9 Rectangular 0,52 1 0,52

Site corrections:


Separation distance 20) at 3 m d ±0,3 Rectangular 0,17 1 0,17


or 30 m d ±0,0 0,00 1 0,00

Table height 21) at 3 m h ±0,1 k = 2 0,05 1 0,05

or 10 m h ±0,1 k = 2 0,05 1 0,05

or 30 m h ±0,1 k = 2 0,05 1 0,05



CISPR 16-4-2 IEC:2003 – 29 –

Table A.6 Horizontally polarised radiated disturbances from 200 MHz to 1 GHz using a log-periodic antenna at a distance of 3 m, 10 m, or 30 m



function

dB dB



Log-periodic antenna factor 12) AF 2,0 k = 2 1,00 1 1,00





Noise floor proximity 6) Vnf 0,5 k=2 0,25 1 0,25


Log-periodic antenna corrections:






Phase centre location 16) at 3 m Aph ±1,0 Rectangular 0,58 1 0,58

or 10 m Aph ±0,3 Rectangular 0,17 1 0,17


Cross-polarisation 17) Acp ±0,9 Rectangular 0,52 1 0,52

Balance 18) Abal 0,0 0,00 1 0,00

Site corrections:




or 30 m d ±0,0 0,00 1 0,00


or 10 m h ±0,1 k = 2 0,05 1 0,05

or 30 m h ±0,1 k = 2 0,05 1 0,05



CISPR 16-4-2 IEC:2003 – 31 –

Table A.7 – Vertically polarised radiated disturbances from 200 MHz to 1 GHz using a log-periodic antenna at a distance of 3 m, 10 m, or 30 m



function

dB dB



Log-periodic antenna factor 12) AF 2,0 k = 2 1,00 1 1,00





Noise floor proximity 6) Vnf 05 k = 2 0,25 1 0,25


Log-periodic antenna corrections:






Phase centre location 16) at 3 m Aph ±1,0 Rectangular 0,58 1 0,58



Cross-polarisation 17) Acp ±0,9 Rectangular 0,52 1 0,52

Balance 18) Abal 0,0 0,00 1 0,00

Site corrections:




or 30 m d ±0,0 0,00 1 0,00


or 10 m h ±0,1 k = 2 0,05 1 0,05

or 30 m h ±0,1 k = 2 0,05 1 0,05



CISPR 16-4-2 IEC:2003 – 33 –

A.5 Comments on the estimates of input quantities

The uncertainty associated with an estimate xi of an input quantity in the above tables is the largest uncertainty considered likely within the frequency range covered by the table, provided that it is consistent with the measuring apparatus specification tolerances in CISPR 16-1. Superscripts to input quantities refer to the numbered comments below. The expanded uncertainties provide the values of Ucispr in Table 1.

The standard uncertainty u(xi) is calculated by dividing the value of the uncertainty associated with xi by a factor which depends on the probability distribution of that uncertainty and on the level of confidence associated with the value. For a U-shaped, rectangular or triangular probability distribution, where Xi is estimated to lie between (xi – a–) and (xi + a+) with

a level of confidence of 100 %, u(xi) is taken as a/ 2 , a/ 3 , or a/ 6 respectively, where

a = (a+ + a–)/2 is the half-width of the probability distribution. For a normal probability distribution, the divisor is 2 if the value of the uncertainty associated with xi has a level of confidence of 95 % (the value is twice the experimental standard deviation), or 1 if the value of the uncertainty associated with xi has a level of confidence of 68 % (the value is the experimental standard deviation).

A correction is compensation for a systematic error. A correction may be known from calibration reports or from calculation. A correction which is not known, but is considered to be equally likely to be positive or negative, is taken to be zero. All corrections are assumed to have been applied, in accordance with the model. Every correction has an associated uncertainty.

The assumptions which led to the values in the above tables may not be appropriate for a particular test-laboratory. When a test-laboratory evaluates its expanded measurement instrumentation uncertainty Ulab, it must consider the information available on its particular measuring system, including equipment characteristics, the quality and currency of calibration data, the known or likely probability distributions, and measurement procedures. A test-laboratory may find it advantageous to evaluate its uncertainties over subdivisions of the frequency range, particularly if a dominant uncertainty varies significantly over that range.

A note following a comment is intended to provide some guidance to test-laboratories confronted with data or situations different to those assumed here.

1) Receiver readings will vary for reasons which include measuring system instability, receiver noise, and meter scale interpolation errors.

The estimate of Vr is the mean of many readings, with a standard uncertainty given by the experimental standard deviation of the mean (k = 1).

2) An estimate of the attenuation Lc of the connection between the receiver and the AMN, absorbing clamp, or antenna, was assumed to be available from a calibration report, along with an expanded uncertainty and a coverage factor.

NOTE If the estimate of attenuation Lc is obtained from manufacturer’s data for a cable or attenuator, a rectangular probability distribution having a half-width equal to the manufacturer’s specified tolerance on the attenuation may be assumed. If the connection is a cable and attenuator in tandem, with manufacturer’s data available on each, Lc has two components, each with its own rectangular probability distribution.

3) An estimate of the AMN voltage division factor Lamn was assumed to be available from a calibration report, along with an expanded uncertainty and a coverage factor.

CISPR 16-4-2 IEC:2003 – 35 –

4) An estimate of the correction Vsw for receiver sine-wave voltage accuracy was assumed to be available from a calibration report, along with an expanded uncertainty and a coverage factor.

NOTE If a calibration report states only that the receiver sine-wave voltage accuracy is within the CISPR 16-1

tolerance ( 2 dB), then the estimate of the correction Vsw should be taken as zero with a rectangular probability distribution having a half-width of 2 dB.

5) In general it is impractical to correct for imperfect receiver pulse response characteristics.

A verification report stating that the receiver pulse amplitude response complies with the

CISPR 16-1 tolerance of 1,5 dB for peak, quasi-peak, average, or RMS detection was

assumed to be available. The correction Vpa was estimated to be zero with a rectangular probability distribution having a half-width of 1,5 dB.

The CISPR 16-1 tolerance for pulse repetition rate response varies with repetition rate and detector type. A verification report stating that the receiver pulse repetition rate responses

comply with the CISPR 16-1 tolerances was assumed to be available. The correction Vprwas estimated to be zero with a rectangular probability distribution having a half-width of 1,5 dB, a value considered to be representative of the various CISPR 16-1 tolerances.

NOTE If the pulse amplitude response or the pulse repetition rate response is verified to be within dB of

the CISPR specification ( 1,5), the correction for that response may be estimated to be zero with a rectangular probability distribution having a half-width of dB.

If a disturbance produces a continuous wave signal at the detector, pulse response corrections need not be considered.

6) The noise floor of a CISPR receiver is usually sufficiently far below the disturbance voltage limit or the disturbance power limit that its effect is negligible on measurement results near those limits. However for radiated disturbances, the proximity of the receiver noise floor may influence measurement results near the radiated disturbance limit.

For radiated disturbance measurement, the correction Vnf was estimated to be zero with an expanded uncertainty of 0,5 dB and a coverage factor of 2.

7) In general, the receiver port of an AMN, absorbing clamp or antenna will be connected to port 1 of a two-port network whose port 2 is terminated by a receiver of reflection

coefficient r. The two-port network, which might be a cable, attenuator, attenuator and cable in tandem, or some other combination of components, can be represented by its S-parameters. The mismatch correction is then

re22122r11e10 )1)(1(log20 SSSM

where e is the reflection coefficient seen looking into the receiver port of the AMN or absorbing clamp with the EUT connected, or looking into the output port of the antenna

when it is set up for disturbance measurement. All parameters are with respect to 50 .

When only the magnitudes, or extremes of magnitudes, of the parameters are known, it is not possible to calculate M, but its extreme values M are not greater than

221re2211re22r11e10 1log20 SSSSSM

The probability distribution of M is approximately U-shaped, with width not greater than

( M M ) and standard deviation not greater than the half-width divided by 2 .

For disturbance voltage and disturbance power measurements, e is a function of the EUT impedance which is, in general, unknown and unbounded.

CISPR 16-4-2 IEC:2003 – 37 –

Worst-case reflection coefficient magnitudes of e = 1 were assumed. It was also assumed that the connection to the receiver was a well-matched cable ( S11 <<1, S22 <<1) of

negligible attenuation ( S21 1), and that the receiver RF attenuation was 10 dB or more,

for which the CISPR 16-1 tolerance of VSWR (voltage standing wave ratio) 1,2:1 implies

r 0,09.

For radiated disturbance measurements, an antenna specification of VSWR 2,0:1 was

assumed, implying e 0,33. It was also assumed that the connection to the receiver was a well-matched cable ( S11 <<1, S22 <<1) of negligible attenuation ( S21 1), and that the receiver RF attenuation was 0 dB, for which the CISPR 16-1 tolerance of

VSWR 2,0:1 implies r 0,33.

The estimate of the correction M was zero with a U-shaped probability distribution having width equal to the difference ( M M ).

NOTE The expressions for M and M show that mismatch error can be reduced by increasing the attenuation of the well-matched two-port network preceding the receiver. The penalty is a reduction in measurement sensitivity.

For some antennas at some frequencies, the VSWR may be much greater than 2,0:1.

Precautions may be needed to ensure that the impedance seen by the receiver complies with the CISPR 16-1

specification of VSWR 2,0:1 when a complex antenna is used.

If an AMN or absorbing clamp is calibrated to the output port of an attenuator connected permanently to it, the effect of the EUT impedance on the mismatch error will be reduced as the value of the attenuation is increased.

8) The impedance tolerance in CISPR 16-1 for a 50 /50 H + 5 AMN or a 50 /50 H AMN requires the impedance magnitude to be within 20 % of the magnitude of the nominal

impedance when the receiver port is terminated in 50 . The absence of any CISPR 16-1 restriction on the impedance phase gives rise to an unlimited measurement uncertainty on the voltage developed across the AMN by an EUT.

It was assumed that the impedance presented by the AMN EUT port when the receiver

port was terminated in 50 lay within a circle centred on the nominal impedance on the complex-impedance plane, that circle having a radius of 20 % of the nominal impedance magnitude. This placed a tolerance on the impedance phase commensurate with that on

the impedance magnitude. The estimate of the correction Z was zero with a probability distribution bounded by the extremes from all combinations of the constrained AMN impedance and unconstrained EUT impedance over the defined frequency range. A triangular probability distribution was assumed because there is only a small chance of encountering the particular combinations of frequency, AMN impedance and EUT impedance needed to produce those extremes.

9) An estimate of absorbing clamp insertion loss Lac was assumed to be available from a calibration report, along with an expanded uncertainty and a coverage factor.

10) Mains disturbances which are inadequately isolated from the absorbing clamp current transformer may affect the receiver reading. Fixing ferrite absorber along the mains cord near the mains supply, or using an AMN to provide a filtered mains supply, may be necessary to reduce the effect of mains disturbances.

It was assumed that any mains disturbances were negligible, or their effect had been reduced to a negligible amount by appropriate suppression measures. The estimate of the correction MD was zero with an uncertainty of zero.

NOTE If mains disturbances are not negligible and their effect on the receiver reading has not been reduced adequately by appropriate suppression measures, a non-zero estimate of the correction and its uncertainty should be included.

CISPR 16-4-2 IEC:2003 – 39 –

11) Measurements of disturbance power using an absorbing clamp are sensitive to the surrounding environment, including the nature and proximity of room surfaces. It is difficult to determine the correction E needed to account for the difference between the environment in which the absorbing clamp is calibrated and that in which it is used.

The estimate of the correction E was zero with a standard deviation derived from values obtained when a common artefact was measured in different environments.

NOTE If an absorbing clamp is calibrated and used in the same environment, the correction E need not be considered.

12) An estimate of the free space antenna factor AF was assumed to be available from a calibration report, along with an expanded uncertainty and a coverage factor.

13) When an antenna factor is calculated by interpolation between frequencies at which calibration data are available, the uncertainty associated with that antenna factor depends on the frequency interval between calibration points and the variability of antenna factor with frequency. Plotting calibrated antenna factor against frequency helps visualise the situation.

The estimate of the correction AFf for antenna factor interpolation error was zero, with a rectangular probability distribution having a half-width of 0,3 dB.

NOTE At any frequency for which a calibrated antenna factor is available, the correction AFf need not be considered.

14) The height dependence of antenna factor for a complex antenna will differ from that for a dipole antenna, which is the CISPR 16-1 designated reference antenna from 30 MHz to 300 MHz.

The estimate of the correction AFh was zero with a rectangular probability distribution having a half-width evaluated from the behaviour of biconical and log-periodic antenna factor with height.

NOTE If a dipole is the measuring antenna, or at frequencies above 300 MHz, the correction AFh need not be considered.

15) CISPR 16-1 requires the responses of a complex antenna in the direction of the direct ray and in the direction of the ground-reflected ray to be within 1 dB of the maximum response. To meet this requirement, the boresight of the complex antenna may need to be

tilted downwards, particularly at separations of less than 10 m. The correction Adir for the effect of directivity is 0 dB for an antenna having a uniform pattern in the vertical plane, and between 0 dB and +1 dB for an antenna having a non-uniform pattern in the vertical plane.

A horizontally-polarised biconical antenna was assumed to have a uniform pattern in the vertical plane. A vertically polarised biconical antenna, and a horizontally or vertically polarised log-periodic antenna were assumed to require a correction Adir of up to +1 dB at separations of 3 m and 10 m, but not more than +0,5 dB at a separation of 30 m.

The estimate of the correction Adir was zero with a rectangular probability distribution having the appropriate width.

NOTE A non-zero estimate of Adir with reduced uncertainty could be evaluated from the known pattern of the measuring antenna, and applied as a function of frequency and separation. If a dipole is the measuring antenna, CISPR 16-1 imposes no explicit requirements on the responses in the directions of the direct ray and

ground-reflected ray, and the correction Adir need not be considered.

16) The correction Aph for phase centre location is negligible for a biconical antenna, but the change in phase-centre location with frequency for a log-periodic antenna causes a deviation from the required separation.

For a log-periodic antenna, the estimate of the correction Aph was zero with a rectangular probability distribution having a half-width evaluated by considering the effect of an error

of 0,35 m in the separation and assuming that field strength is inversely proportional to separation.

NOTE If a dipole is the measuring antenna, the correction Aph is negligible.

CISPR 16-4-2 IEC:2003 – 41 –

17) The cross-polarisation response of a biconical antenna was considered to be negligible.

The estimate of the correction Acp for cross-polarisation response of a log-periodic antenna was zero with a rectangular probability distribution having a half-width of 0,9 dB, corresponding to the CISPR 16-1 cross-polarisation response tolerance of 20 dB.

NOTE If a dipole is used as the measuring antenna the correction Acp is negligible.

18) The effect of an unbalanced antenna is greatest when the input coaxial cable is aligned

parallel to the antenna elements. The estimate of the correction Abal for antenna unbalance was zero with a rectangular probability distribution having a half-width evaluated from the performance of commercially available antennas.

19) The magnitude Dmax of the maximum difference between theoretical site attenuation on the one hand, and measured site attenuation increased by the site attenuation measurement uncertainty on the other, provides an indication of the effect that site imperfection may have on a disturbance measurement. The CISPR 16-1 tolerance for this

difference is 4 dB. However, the measurement uncertainty associated with the CISPR 16-1 site attenuation measurement method is usually large, and dominated by the two antenna factor uncertainties. Therefore a site which meets the 4 dB tolerance is unlikely to have imperfections sufficient to cause errors of 4 dB in disturbance measurements. In recognition of this, a triangular probability distribution is assumed for the correction SA.

The estimate of the correction SA was zero with a triangular probability distribution having a half-width of 4 dB.

Future improvement of the site validation methods in CISPR 16-1 will reduce the tolerance specification.

NOTE If Dmax is less than 4 dB, the estimate of the correction SA may be taken as zero with a triangular probability distribution of half-width Dmax.

20) The error in separation arises from the errors in determining the perimeter of the EUT,

distance measurement, and antenna mast tilt. The estimate of the correction d for separation error was zero with a rectangular probability distribution having a half-width

evaluated from assuming a maximum separation error of 0,1 m, and that field strength is inversely proportional to separation over that distance margin.

21) The error caused by the equipment under test being placed on a table of other than

nominal height of 0,8 m. The correction h to be applied to the maximum measured field

strength to correct for a table height which deviates by up to 0,01 m from nominal was estimated to be zero, with a normal probability distribution having an expanded uncertainty of 0,1 dB at the 95 % level of confidence.

CISPR 16-4-2 IEC:2003 – 43 –

Bibliography

[1] International Vocabulary of Basic and General Terms in Metrology, ISO, 1993, ISBN 92-67-01075-1.

[2] ISO/IEC GUIDE EXPRES:1995, Guide to the Expression of Uncertainty in Measurement.

[3] TAYLOR, BN. and KUYATT, CE. Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results, United States Department of Commerce Technology Administration, National Institute of Standards and Technology, September 1994, NIST Technical Note 1297.

[4] Expression of the Uncertainty of Measurement in Calibration. European Cooperation for Accreditation of Laboratories, EAL-R2, April 1997; and Supplement 1 to EAL-R2, EAL-R2-S1, November 1997.

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en 55016-4-2 2005

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