SIST EN 50357:2002
(Main)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
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
Relations
Standards Content (Sample)
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.
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SIST EN 50357:2002
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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
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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.
__________
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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
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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:
1)
� 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
2)
3. Similar techniques proposed or adopted by IEC , especially in the case of desktop equipment [5].
4. Other, specifically referenced techniques.
1)
International Commission on Non-Ionising Radiation Protection
2)
International Electrotechnical Committee
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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
-2
Current density J ampere per square metre Am
-1
Electric field strength E volt per metre Vm
-2
Electric flux density D coulomb per square metre Cm
-1
Electric conductivity siemens per metre Sm
�
Frequency f hertz Hz
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EN 50357:2001 – 6 –
-1
Magnetic field strength H ampere per metre Am
2
Magnetic flux density B tesla (Vs/m)T
-3
Mass density kilogram per cubic metre kgm
�
-1
Permeability henry per metre Hm
�
-1
Permittivity farad per metre Fm
�
-2
Power density S watt per square metre Wm
-1
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
�
0
-7 -1
Permeability of free space
� 4� x 10 Hm
0
Impedance of free space Z 120� (or 377) �
0
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
1
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
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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
F
E �
q
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
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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 )
0
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
-1
where µ is the permeability of the medium expressed in henry per metre (Hm )
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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
-1
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.
2
E
2
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.
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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
n
2
X � ��X
� n
1
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
� �
� �
–1
SAR is expressed in units of watts per kilogram (Wkg ).
NOTE SAR can be calculated by:
2
� E
i
SAR �
�
dT
SAR �c
i
dt
at t
0
where
E : rms value of the electric field strength in the tissue in V/m
i
� : conductivity of body tissue in S/m
3
� : density of body tissue in kg/m
c : heat capacity of body tissue in J/kg K
i
dT
: initial time derivative of temperature in body tissue in K/s
dt
3.1.34
wavelength
the wavelength (�) of an electromagnetic wave is related to the frequency (f) and velocity (c) by the
expression
c
� �
f
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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
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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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