Evaluation of human exposure to electromagnetic fields from devices used in Electronic Article Surveillance (EAS), Radio Frequency Identification (RFID) and similar applications

D109/093: CLC/TC 211 renumbered CLC/TC 106X

Ermittlung der Exposition von Personen gegenüber elektromagnetischen Feldern von Geräten, die in der elektronischen Artikelüberwachung (en: EAS), Hochfrequenz-Identifizierung (en: RFID) und ähnlichen Anwendungen verwendet werden

Evaluation de l'exposition humaine aux champs électromagnétiques (EMFs) émis par les dispositifs utilisés pour la surveillance électronique des objets (EAS), l'identification par radiofréquence (RFID) et les applications similaires

Evaluation of human exposure to electromagnetic fields from devices used in Electronic Article Surveillance (EAS), Radio Frequency Identification (RFID) and similar applications

General Information

Status
Withdrawn
Publication Date
31-Dec-2001
Withdrawal Date
19-Feb-2012
Current Stage
9900 - Withdrawal (Adopted Project)
Start Date
20-Feb-2012
Due Date
14-Mar-2012
Completion Date
20-Feb-2012

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SLOVENSKI STANDARD
SIST EN 50357:2002
01-januar-2002
Evaluation of human exposure to electromagnetic fields from devices used in
Electronic Article Surveillance (EAS), Radio Frequency Identification (RFID) and
similar applications

Evaluation of human exposure to electromagnetic fields from devices used in Electronic

Article Surveillance (EAS), Radio Frequency Identification (RFID) and similar
applications
Ermittlung der Exposition von Personen gegenüber elektromagnetischen Feldern von
Geräten, die in der elektronischen Artikelüberwachung (en: EAS), Hochfrequenz-
Identifizierung (en: RFID) und ähnlichen Anwendungen verwendet werden

Evaluation de l'exposition humaine aux champs électromagnétiques (EMFs) émis par les

dispositifs utilisés pour la surveillance électronique des objets (EAS), l'identification par

radiofréquence (RFID) et les applications similaires
Ta slovenski standard je istoveten z: EN 50357:2001
ICS:
13.280 Varstvo pred sevanjem Radiation protection
SIST EN 50357:2002 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN 50357:2002
---------------------- Page: 2 ----------------------
SIST EN 50357:2002
EUROPEAN STANDARD EN 50357
NORME EUROPÉENNE
EUROPÄISCHE NORM October 2001
ICS 13.280; 33.100.01
English version
Evaluation of human exposure to electromagnetic fields
from devices used in Electronic Article Surveillance (EAS),
Radio Frequency Identification (RFID) and similar applications
Evaluation de l'exposition humaine aux Ermittlung der Exposition von Personen
champs électromagnétiques (EMFs) gegenüber elektromagnetischen Feldern
émis par les dispositifs utilisés pour la von Geräten, die in der elektronischen
surveillance électronique des objets Artikelüberwachung (en: EAS),

(EAS), l'identification par radiofréquence Hochfrequenz-Identifizierung (en: RFID)

(RFID) et les applications similaires und ähnlichen Anwendungen verwendet
werden

This European Standard was approved by CENELEC on 2001-07-03. 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, Czech Republic,

Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands,

Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2001 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 50357:2001 E
---------------------- Page: 3 ----------------------
SIST EN 50357:2002
EN 50357:2001 – 2 –
Foreword

This European Standard was prepared by the Technical Committee CENELEC TC 106X (former TC 211),

Electromagnetic fields in the human environment.

The text of the draft was submitted to the Unique Acceptance Procedure and was approved by CENELEC as

EN 50357 on 2001-07-03.
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) 2002-07-01
- latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2004-07-01
Annexes designated "informative" are given for information only.
In this standard, annexes A and B are informative.
__________
---------------------- Page: 4 ----------------------
SIST EN 50357:2002
– 3 – EN 50357:2001
Contents

Foreword.................................................................................................................................................... 1

Introduction ............................................................................................................................................... 4

1 Scope .................................................................................................................................................. 5

2 Physical quantities, units and constants........................................................................................... 5

2.1 Quantities ...................................................................................................................................... 5

2.2 Constants ...................................................................................................................................... 6

3 Terms and definitions......................................................................................................................... 6

3.1 General ......................................................................................................................................... 6

3.2 Specific for EAS, RFID and similar applications............................................................................ 11

4 Measurements and calculations for equipment compliance .......................................................... 14

4.1 Simple measurements to show compliance with derived reference levels..................................... 14

4.2 Measurements and analysis to show compliance with basic restrictions ....................................... 23

4.3 Numerical modelling to show compliance with basic restrictions................................................... 27

4.4 Measurement of limb and contact currents................................................................................... 29

5 Measurements for field monitoring.................................................................................................. 29

5.1 Field measurements .................................................................................................................... 29

5.2 Additional evaluation.................................................................................................................... 30

6 Exposure from sources with multiple frequencies or complex waveforms................................... 30

7 Uncertainty........................................................................................................................................ 30

7.1 Evaluating uncertainties............................................................................................................... 31

7.2 Examples of typical uncertainties ................................................................................................. 31

7.3 Overall uncertainties .................................................................................................................... 32

Annex A (informative) Characteristics of equipment ........................................................................... 35

A.1 EAS Equipment ........................................................................................................................... 35

A.2 EAS desktop and activation/deactivation equipment..................................................................... 39

A.3 RFID equipment........................................................................................................................... 39

Annex B (informative) Information for numerical modelling................................................................ 45

B.1 Introduction.................................................................................................................................. 45

B.2 Anatomical models....................................................................................................................... 45

B.3 Electrical properties of tissue........................................................................................................ 46

B.4 Comparison of induced currents, modelled using different sizes of prolate spheroid ..................... 49

---------------------- Page: 5 ----------------------
SIST EN 50357:2002
EN 50357:2001 – 4 –
Introduction

This document presents procedures for the evaluation of human exposure to electromagnetic fields (EMF’s)

from Devices used in electronic article surveillance (EAS), radio frequency identification (RFID) and similar

applications. The work has been carried out in response to:

� The ICNIRP Guidelines for limiting exposure to time-varying electric, magnetic and electromagnetic

fields (up to 300 GHz) [1];

� European Council Recommendation 1999/519/EC on the limitation of exposure of the general public to

electromagnetic fields 0-300 GHz (the EC Recommendation) [2];

� European Council Directive 73/23/EEC on the harmonisation of the laws of member states relating to

electrical equipment designed for use within certain voltage limits (the LV Directive) [3];

� European Council Directive 1999/5/EC on radio equipment and telecommunications terminal equipment

and the mutual recognition of their conformity (the R&TTE Directive) [4].

The techniques presented in this document may also be used to demonstrate compliance to other National

or International requirements.

Electromagnetic fields interact with the human body and other biological systems through a number of

physical mechanisms. The main mechanisms of interaction are based on nervous system effects and

heating. These effects are dependent on frequency and are defined by biologically relevant quantities such

as magnetic flux density, induced current density and specific absorption rate. These quantities are not

directly measurable so they must be determined either, by calculation for each case, or by measuring a

reference quantity which has a pre-derived relationship to them.

The examples used in this document are taken from the EC Recommendation and from the ICNIRP

Guidelines. They each contain a series of Basic Restrictions for magnetic flux density, induced current

density, power density and specific absorption rate as well as a series of derived Reference Levels

In any particular exposure situation, measured or calculated values can be compared to the appropriate

reference level. The reference levels are generally obtained from the basic restriction by mathematical

modelling and laboratory experimentation at specific frequencies. They reflect maximum coupling of the fields

to the exposed human being, thereby providing maximum protection. Respect of the reference level will

ensure respect of the relevant basic restriction. If the measured value exceeds the reference level, it does not

necessarily follow that the basic restriction is also exceeded. Under those circumstances, more detailed

evaluation techniques will be necessary which are specific to that type of equipment and exposure.

This document adopts a staged approach to compliance assessment. The first stage is a simple measurement

against the appropriate derived Reference Levels. If the device meets these, there is no requirement for further

assessment. Stage 2 is a more complex series of measurements, coupled with analysis techniques. Again, if

the device meets the appropriate levels, there is no requirement for further assessment. Stage 3 requires

detailed modelling and analysis to show compliance with the Basic Restrictions. Device compliance can be

shown using any one of the stages; it is not necessary to use more than one, unless an assessment using

Stages 1 or 2 fails to demonstrate compliance.

The devices covered by this document normally have non-uniform field patterns. Often these devices have a

very rapid reduction of field strength with distance and operate under near-field conditions where the

relationship between electric and magnetic fields is not constant. This, together with typical exposure

conditions for different device types, is detailed in annex A.
Measurements and methods are derived with reference to:
1. Work carried out within CENELEC

2. Notes and explanatory text from the EC Recommendation and the ICNIRP Guidelines

3. Similar techniques proposed or adopted by IEC , especially in the case of desktop equipment [5].

4. Other, specifically referenced techniques.
International Commission on Non-Ionising Radiation Protection
International Electrotechnical Committee
---------------------- Page: 6 ----------------------
SIST EN 50357:2002
– 5 – EN 50357:2001
1 Scope

This European Standard applies to devices used in Electronic Article Surveillance (EAS), Radio Frequency

Identification (RFID) and similar applications. The objective of the Standard is to specify, for such equipment,

the methods for demonstration of compliance with basic restrictions or reference levels related to human

exposure to electromagnetic fields.

The Council Directive 1999/5/EC [4], Article 3.1(a), defines essential requirements for equipment that is

either radio equipment or telecommunications equipment or both; with regard to the protection of the health

and safety of the user and any other person. This document may be used for demonstration of compliance

to the Council Directive with reference to human exposure to electromagnetic fields (EMF’s). There are

additional requirements covered by Article 3.1(a), which are not included in this document.

The Council Directive 73/23/EEC [3], Article 2, stipulates that the Member States take all appropriate

measures to ensure that electrical equipment may be placed on the market only if, having been constructed

in accordance with good engineering practice in safety matters in force in the Community, it does not

endanger the safety of persons, domestic animals or property when properly installed and maintained and

used in applications for which it was made. The principal elements of those safety objectives are listed in

annex I clause 2b. This document may be used for demonstration of compliance to the Council Directive

only with reference to human exposure to electromagnetic fields (EMF’s). There are additional requirements

covered by Article 2 and annex I clause 2b, which are not included in this document.

The Council Recommendation 1999/519/EC [2] provides Basic Restrictions and derived Reference Levels

for exposure of the general public in the areas where they spend significant time. This document may be

used for demonstration of equipment compliance to the Council Recommendation on this basis, but there

may be additional specific National or International requirements which are not included.

The ICNIRP Guidelines [1] provide Basic Restrictions and derived Reference Levels for both occupational

and general public exposure. This document may be used for demonstration of equipment compliance to

ICNIRP Guidelines on this basis, but there may be additional specific National or International requirements

which are not included.

Other Standards can apply to products covered by this document. In particular this document is not

designed to assess the electromagnetic compatibility with other equipment, medical or otherwise. It does not

reflect any product safety requirements other than those specifically related to human exposure to

electromagnetic fields.

It is also possible to use this document as a basis to demonstrate compliance to other National and

International Guidelines or Requirements with regard to human exposure from EMF’s. In these cases, other

Restrictions and Levels may be used.
2 Physical quantities, units and constants
2.1 Quantities
The internationally accepted SI units are used throughout this document
Quantity Symbol Unit Dimension
Current density J ampere per square metre Am
Electric field strength E volt per metre Vm
Electric flux density D coulomb per square metre Cm
Electric conductivity siemens per metre Sm
Frequency f hertz Hz
---------------------- Page: 7 ----------------------
SIST EN 50357:2002
EN 50357:2001 – 6 –
Magnetic field strength H ampere per metre Am
Magnetic flux density B tesla (Vs/m)T
Mass density kilogram per cubic metre kgm
Permeability henry per metre Hm
Permittivity farad per metre Fm
Power density S watt per square metre Wm
Specific absorption rate SAR watt per kilogram Wkg
Wavelength metre m
Temperature T kelvin K
2.2 Constants
Physical Constant Symbol Magnitude
8 -1
Velocity of light c 2,997 x 10 ms
-12 -1
Permittivity of free space 8,854 x 10 Fm
-7 -1
Permeability of free space
� 4� x 10 Hm
Impedance of free space Z 120� (or 377) �
3 Terms and definitions
3.1 General
3.1.1
average (temporal) absorbed power (P )
avg
the time – averaged rate of energy transfer defined by:
t 2
P � P(t)dt
avg
t �t
2 1 t1

where t and t are the start and stop time of the exposure (the period t – t is the exposure duration)

1 2 2 1
3.1.2
averaging time (t )
avg

the appropriate time over which exposure is averaged for purposes of determining compliance

3.1.3
Basic Restrictions

restrictions are the restrictions on exposure to time-varying electric, magnetic, and electromagnetic fields that

are based directly on established health effects
3.1.4
conductivity (�)

the ratio of the conduction – current density in a medium to the electric field strength

---------------------- Page: 8 ----------------------
SIST EN 50357:2002
– 7 – EN 50357:2001
3.1.5
contact current

current flowing into the body by touching a conductive object in an electromagnetic field

3.1.6
current density (J)
the electromagnetic field induced current per unit area inside the body
3.1.7
dielectric constant (�)
see permittivity
3.1.8
duty factor (or duty cycle)

the ratio of pulse duration to the pulse period of a periodic pulse train. Also, may be a measure of the

temporal transmission characteristic of an intermittently transmitting RF source such as a paging antenna

by dividing average transmission duration by the average period for transmissions. A duty factor of 1,0

corresponds to continuous operation
3.1.9
electric field strength (E)

the magnitude of a field vector at a point that represents the force (F) on an infinitely small charge (q) divided

by the charge
E �
3.1.10
electric flux density (D)

the magnitude of a field vector that is equal to the electric field strength (E) multiplied by the permittivity (�)

D��E
3.1.11
energy density

the energy impinging per unit area normal to the direction of the electromagnetic wave propagation

3.1.12
exposure

exposure occurs whenever and wherever a person is subjected to electric, magnetic or electromagnetic

fields or to contact current other than those originating from physiological processes in the body and other

natural phenomena
3.1.13
exposure level

The value of the quantity used when a person is exposed to electromagnetic fields or contact currents

3.1.14
exposure, direct effect of

result of a direct interaction in the exposed human body from exposure to electromagnetic fields

3.1.15
exposure, partial body

partial body exposure results when fields are substantially non-uniform over the body. Fields that are non-

uniform over volumes comparable to the human body may occur due to highly directional sources, standing

waves, re-radiating sources or in the near field
---------------------- Page: 9 ----------------------
SIST EN 50357:2002
EN 50357:2001 – 8 –
3.1.16
exposure, non-uniform

non-uniform exposure levels result when fields are non-uniform over volumes comparable to the whole

human body. This may occur due to standing waves, scattered radiation or in the near field. See “exposure,

partial body”
3.1.17
far-field region

that region of the field of an antenna where the angular field distribution is essentially independent of the

distance from the antenna. In this region (also called the free space region), the field has a predominantly

plane-wave character, i.e. locally uniform distribution of electric field strength and magnetic field strength in

planes transverse to the direction of propagation
3.1.18
induced current

current induced inside the body as a result of direct exposure to electromagnetic fields

3.1.19
intrinsic impedance of free space (Z )

the ratio of the electric field strength to the magnetic field strength of a propagating electromagnetic wave in

free space. This does not apply in the near-field region
3.1.20
magnetic flux density (B)

the magnitude of a field vector that is equal to the magnetic field H multiplied by the permeability (µ) of the

medium
B��H
3.1.21
magnetic field strength (H)

the magnitude of a field vector in a point that results in a force (F) on a charge (q) moving with velocity (v)

F � q�� � �H �

[or magnetic flux density divided by permeability of the medium, see “magnetic flux density”]

3.1.22
multiple frequency fields
the superposition of two or more electromagnetic fields of differing frequency
3.1.23
near-field region

a region generally in proximity to an antenna or other radiating structure, in which the electric and magnetic

fields do not have a substantially plane-wave character, but vary considerably from point to point. The near–

field region is further subdivided into two sub-regions. The reactive near-field region is closest to the

radiating structure and contains most or nearly all of the stored energy. The radiating near-field region is

where the radiation field predominates over the reactive field, but lacks substantial plane-wave character and

is complicated in structure
3.1.24
permeability (µ)

the property of a material which defines the relationship between magnetic flux density B and magnetic field

strength H. It is commonly used as the combination of the permeability of free space and the relative

permeability for specific dielectric materials
µ = µ µ = B/H
R 0
where µ is the permeability of the medium expressed in henry per metre (Hm )
---------------------- Page: 10 ----------------------
SIST EN 50357:2002
– 9 – EN 50357:2001
3.1.25
permittivity, (�)

the property of a dielectric material (e.g. biological tissue) which defines the relationship between electrical

flux density D and electrical field strength E. It is commonly used as the combination of the permittivity of

free space and the relative permittivity (or dielectric constant) for specific dielectric materials

ε = µ µ = D/H
R 0
where � is the permittivity of the medium expressed in farads per metre (Fm )
3.1.26
polarisation

that property of electromagnetic fields describing the time-varying direction and amplitude of the electric field

vector: specifically, the figure traced as a function of time by the extremity of the E-Field vector at a fixed

location in space, as observed along the direction of propagation. In general, the figure is elliptical and it is

traced in a clockwise or counter clockwise sense. The commonly referenced circular and linear polarisations

are obtained when the ellipse becomes a circle or a straight line, respectively. Clockwise sense rotation of

the electric vector is designated right – hand polarisation and counter clockwise sense rotation is designated

left-hand polarisation
3.1.27
power density (S)

power per unit area normal to the direction of electromagnetic wave propagation. For plane waves the

power density (S), electric field strength (E) and magnetic field strength (H) are related by the impedance of

free space, i.e. 377 ohms

NOTE Although many survey instruments indicate power density units, the actual quantities measured are E or H, or the square of

those quantities.
S � � 377H � EH
377
-1 -1 -2

In particular where E and H are expressed in units of Vm and Am , respectively, and S in Wm .

It should be noted that the value of 377 � is only valid for free space, far field measurement conditions (and does not apply for inductive

devices operating in the reactive near field).
3.1.28
power density, average (temporal)

the instantaneous power density integrated over a source repetition period. This averaging is not to be

confused with the measurement averaging time
3.1.29
power density, plane-wave equivalent

commonly used term associated with any electromagnetic wave, equal in magnitude to the power density of

a plane wave having the same electric (E) or magnetic (H) field strength
3.1.30
root-mean-square (rms)

the effective value or the value associated with joule heating, of a periodic electromagnetic wave. The rms

value is obtained by taking the square root of the mean of the squared value of a function

NOTE Although many survey instruments indicate rms, the actual quantity measured is root-sum-square (rss) (equivalent field

strength). The value rss is obtained from three individual rms field strength values, measured in three orthogonal directions combined

disregarding the phases. The measured rss value is the maximum possible (worse case) and can be quite different from the true root-

mean-square (rms) value.
---------------------- Page: 11 ----------------------
SIST EN 50357:2002
EN 50357:2001 – 10 –
3.1.31
root-sum-square (rss)

the effective value or the value associated with joule heating, of a periodic electromagnetic wave. The rss

value is obtained by taking the square root of the sum of the squared value of a function

X � ��X
� n
3.1.32
scattered radiation

an electromagnetic field resulting from currents induced in a secondary, conducting or dielectric object by

electromagnetic waves incident on that object from one or more primary sources. The scattering object is

sometimes called a “re-radiator” or “secondary radiator”
3.1.33
specific absorption rate (SAR)

the time derivative of the incremental electromagnetic energy (dW) absorbed by (dissipated in) an

incremental mass (dm) contained in a volume element (dV) of given mass density (� )

d dW d � dW �
� �
SAR � � � �
� �
� �
dt dm dt �dV
� �
� �
SAR is expressed in units of watts per kilogram (Wkg ).
NOTE SAR can be calculated by:
� E
SAR �
SAR �c
at t
where
E : rms value of the electric field strength in the tissue in V/m
� : conductivity of body tissue in S/m
� : density of body tissue in kg/m
c : heat capacity of body tissue in J/kg K
: initial time derivative of temperature in body tissue in K/s
3.1.34
wavelength

the wavelength (�) of an electromagnetic wave is related to the frequency (f) and velocity (c) by the

expression
� �
---------------------- Page: 12 ----------------------
SIST EN 50357:2002
– 11 – EN 50357:2001
3.2 Specific for EAS, RFID and similar applications
3.2.1
active tags

tags which use batteries as a partial or complete source of power. They are further differentiated by

separating them into those with replaceable batteries and those with batteries that are sealed for life as an

integral part of the tag
3.2.2
activator
a device which changes inactive transponders so that they are able to transpond
3.2.3
air interface

the conductor-free medium, usually air, between a transponder and the reader through which data

communication is achieved by means of a modulated inductive, capacitive or propagated electromagnetic

field
3.2.4
antenna

antennas are conductive elements that radiate, and/or receive energy in the radio frequency spectrum

3.2.5
bandwidth

the range or band of frequencies in the electromagnetic spectrum within which a system is capable of

receiving and transmitting
3.2.6
capacitive coupling

systems using electric fields as a means of transferring data or power are said to use capacitive coupling.

This is sometimes also referred to as electrostatic coupling
3.2.7
carrier

the frequency used to carry data by appropriate modulation of the carrier waveform

3.2.8
CEPT

Conférence Européenne des Postes et des Télécommunication. The body responsible for European (not

only EC) efficient utilisation of spectrum and regulatory matters
3.2.9
deactivator
a device which changes transponders so that they no longer transpond
3.2.10
electromagnetic coupling

systems using electromagnetic waves (hertzian waves) as a means of transferring data or power are said to

use electromagnetic coupling
3.2.11
electronic article surveillance (EAS)

a system which detects the presence of transponders, which is often used for anti-theft purposes

3.2.12
electrostatic coupling

systems using the induced voltage on a plate as a means of transferring data or power are said to use

electrostatic coupling
---------------------- Page: 13 ----------------------
SIST EN 50357:2002
EN 50357:2001 – 12 –
3.2.13
ERP

effective radiated power (normally expressed in watts.) is the product of the power supplied to the antenna

and its gain relative to a half-wave dipole in a given direction
3.2.14
EIRP

equivalent isotropic radiated power (normally expressed in watts) is the product of the power supplied to the

antenna and the antenna gain in a given direction relative to an isotropic antenna (absolute or isotropic gain)

3.2.15
frequency
the number of times per second that a signal executes a complete cycle
3.2.16
harmonics
multiples of a principal frequency, invariably exhibiting lower amplitudes
3.2.17
inductive coupling

systems using magnetic fields as a means of transferring data or power are said to use inductive coupling

3.2.18
ITU

International Telecommunication Union. The body responsible for world-wide utilisation of the spectrum

3.2.19
memory card
a read/write or re-programmable tag with the size of a credit card
3.2.20
modulat
...

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