IEC TR 62630:2010

Guidance for evaluating exposure from multiple electromagnetic sources

IEC/TR 62630:2010(E) describes exposure evaluation concepts and techniques for the overall exposure level in spatial regions and occupants caused by the simultaneous exposure to multiple narrowband electromagnetic (EM) sources. Throughout this Technical Report, it is assumed that the exposure evaluation occurs under static conditions, i.e., the source position and transmit-mode characteristics (e.g. emitted power, modulation scheme, etc.) of the device(s) under test do not vary significantly over the time required to carry out the evaluation using the chosen evaluation technique (e.g., field measurements). IEC/TR 62630:2010 provides guidance to IEC TC 106 project teams on how to evaluate the combined exposures from multiple electromagnetic (EM) sources in the frequency range 100 kHz to 300 GHz when specific absorption rate (SAR) and equivalent power density (S) are the relevant exposure metrics, as defined by the main international guidelines recommending limits on human exposure to EM fields.

General Information

• Status: Published
• Publication Date: 09-Mar-2010
• ICS: 17.220.20 - Measurement of electrical and magnetic quantities
• ICS: 33.050.10 - Telephone equipment
• Technical Committee: TC 106 - Methods for the assessment of electric, magnetic and electromagnetic fields associated with human exposure
• Drafting Committee: WG 4 - TC 106/WG 4
• Current Stage: PPUB - Publication issued
• Start Date: 10-Mar-2010
• Completion Date: 30-Jun-2010

Overview

IEC TR 62630:2010 - Guidance for evaluating exposure from multiple electromagnetic sources provides practical, consensus-based guidance for assessing combined human exposure to multiple narrowband electromagnetic (EM) sources in the 100 kHz to 300 GHz frequency range. The report focuses on energy-based exposure metrics - specific absorption rate (SAR) and equivalent power density (S) - and addresses how to estimate overall exposure when several intentional transmitters operate simultaneously under static conditions (source positions and transmit characteristics do not vary significantly during measurement).

Key topics and technical scope

• Frequency and signal scope: Narrowband sources (fractional bandwidth ≤ 10% of centre frequency) in 100 kHz–300 GHz. Wideband/UWB systems are noted but not the primary focus.
• Exposure metrics: Guidance specifically targets SAR (internal/tissue heating) and equivalent power density (external fields).
• Summation techniques: Explains approaches for combining fields from multiple sources, including:
  • Summation of internal fields for SAR and of external fields for power density.
  • Methods for uncorrelated vs correlated sources (e.g., independent transmitters vs beam-steering/adaptive arrays).
  • Vector-sum (accurate) versus conservative scalar-sum approaches and implications when using scalar sensors.
• Device and source classification: Differentiates user-centric vs node-centric devices, single-channel vs band-wide transmitters, and provides practical source classes.
• Measurement considerations: Guidance on selecting appropriate evaluation techniques (field measurements, analytical estimates) and on interpreting results under the assumption of static test conditions.
• Informative annexes: Frequency allocations for common services, analytical support, and worked examples illustrating combined-exposure evaluations.

Practical applications

• Evaluating combined RF exposure around:
  • Multi-band wireless handsets (multiple antennas on the same device)
  • Shared/base-station sites and multi-sector cellular masts
  • Smart antenna arrays and beam-forming systems
• Informing product design and site deployment decisions to manage aggregate exposure
• Supporting test-plan development and exposure assessments used by safety, compliance, and engineering teams

Who should use this technical report

• IEC TC 106 project teams developing exposure standards
• RF and compliance engineers performing exposure assessments (SAR and power-density)
• Health & safety and regulatory specialists assessing aggregate exposure from multiple transmitters
• Test laboratories and certification bodies seeking guidance on summation approaches

Related standards and guidance

• References IEC 62209-1 (human exposure from handheld and body‑mounted wireless devices) and aligns with the main international exposure guidelines that set SAR and power-density limits. IEC TR 62630 does not itself define compliance test methods or regulatory limits - those are covered in product compliance standards and national regulations.

Keywords: IEC TR 62630:2010, electromagnetic exposure, combined exposure, SAR, power density, multiple sources, narrowband, RF safety, IEC TC 106.

Standards Content (Sample)

IEC/TR 62630 ®
Edition 1.0 2010-03
TECHNICAL
REPORT
colour
inside
Guidance for evaluating exposure from multiple electromagnetic sources

IEC/TR 62630:2010(E)
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IEC/TR 62630 ®
Edition 1.0 2010-03
TECHNICAL
REPORT
colour
inside
Guidance for evaluating exposure from multiple electromagnetic sources

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
X
ICS 17.220.20; 33.050.10 ISBN 978-2-88910-776-6
– 2 – TR 62630 © IEC:2010(E)
CONTENTS
FOREWORD.4
INTRODUCTION.6
1 Scope.7
2 Normative references .7
3 Terms, definitions and abbreviations .8
3.1 Terms and definitions .8
3.2 Physical quantities .16
3.3 Constants.16
3.4 Abbreviations .16
3.5 Vector notations .17
4 Overview .17
5 Classification of devices and EM sources .20
5.1 General aspects .20
5.2 Device classification based on the intended use: user-centric versus node-
centric .20
5.3 EM source classification: single-channel versus band-wide transmitters .21
6 Combined exposure from multiple narrowband EM sources .23
6.1 Guidance on the selection of the exposure summation approach.23
6.2 Correlation between signals emitted by different EM sources .24
6.3 Relevant exposure metrics .24
6.4 Combined exposure from uncorrelated EM sources .25
6.5 Combined exposure evaluation of correlated EM sources.25
6.5.1 Accurate estimate of the true field vector sum .25
6.5.2 Conservative combined exposure evaluation using scalar sensors .26
Annex A (informative) Frequency allocations for some common wireless services .29
Annex B (informative) Supporting analytical details.32
Annex C (informative) Examples of combined exposure evaluations .39
Bibliography.46

Figure 1 – Electrical paths from the radiating elements of each panel in a dual-panel
antenna system to a field-point P on the ρ-z symmetry plane .18
Figure 2 – True vector sum of the complex field envelopes produced at the field-point
P by the individual antenna panels in Figure 1 at two different measurement times.19
Figure 3 – Simultaneous exposure at the location X by multiple sector-antennas
belonging to adjacent tri-sector cellular masts (labelled #1 and #2).21
Figure 4 – Different approaches yielding distinct upper-bounds of the field vector-sum .28
Figure B.1 – Vectorial interpretation of inequality (B25), yielding an upper-bound of the
true field vector-sum (red arrow) .37
Figure C.1 – CAD model of the antenna system for a mobile phone, including a
GSM/UMTS antenna and a Bluetooth antenna .39
Figure C.2 – Qualitative description of the individual and combined SAR distributions
for a mobile phone transmitting simultaneously GSM and Wi-Fi signals .40
Figure C.3 – Communications tower shared by different network operators.41
Figure C.4 – Smart antenna formed by 8 vertical 5-element ground-backed dipole
arrays. .42

TR 62630 © IEC:2010(E) – 3 –
Figure C.5 – Power density distributions on the surface Σ (ρ = 1 m) derived via
ρ
Equations (6), (10), and (12) for the 3,5 GHz smart antenna shown in Figure C.4 .44
Figure C.6 – Overestimations produced by Equations (10) and (12) over the exposure
evaluation area Σ (ρ = 1 m) for the 3,5 GHz smart antenna shown in Figure C.4.45
ρ
Table 1 – Source classes: characteristics and examples of source classification .22
Table 2 – Guidance on the selection of suitable evaluation techniques .23
Table A.1 – Frequency allocations and bandwidths for common wireless technologies .29

– 4 – TR 62630 © IEC:2010(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
GUIDANCE FOR EVALUATING EXPOSURE
FROM MULTIPLE ELECTROMAGNETIC SOURCES

FOREWORD
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The main task of IEC technical committees is to prepare International Standards. However, a
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example "state of the art".
IEC/TR 62630, which is a technical report, has been prepared by IEC technical committee 106:
Methods for the assessment of electric, magnetic and electromagnetic fields associated with
human exposure.
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
106/173/DTR 106/196/RVC
Full information on the voting for the approval of this technical report can be found in the
report on voting indicated in the above table.

TR 62630 © IEC:2010(E) – 5 –
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The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
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IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
– 6 – TR 62630 © IEC:2010(E)
INTRODUCTION
This Technical Report provides guidance to IEC TC 106 project teams on how to evaluate the
combined exposures from multiple electromagnetic (EM) sources in the frequency range
100 kHz to 300 GHz when specific absorption rate (SAR) and equivalent power density (S)
are the relevant exposure metrics, as defined by the main international guidelines
recommending limits on human exposure to EM fields.
SAR and power density are energy-intensive exposure metrics related to tissue heating. Other
metrics have been defined in some exposure guidelines to regulate different effects, e.g.,
electro-stimulation. Guidance on evaluating exposure from multiple EM sources based on
these other exposure metrics requires separate further study
This Technical Report considers the combination of exposures from multiple EM sources
a) which reside on the same electronic device (e.g. multi-band mobile phone);
b) arising from multiple devices (e.g. multiple base station antennas);
c) arising from temporally uncorrelated fields (e.g., transmitters operating in different bands);
d) arising from temporally correlated fields (e.g., adaptive (beam-steering) antenna arrays).
Only intentional EM-energy transmitters are considered.
NOTE Evaluation of spurious radiation from non-intentional emitters is addressed in electromagnetic compatibility
(EMC) standards dealing with unwanted EM emissions from electronic devices. The guidance in this Technical
Report is not specifically intended for combining exposures from non-intentional radiating sources, such as EM
leakages from electronic devices that are not designed for purpose of radiated RF emission. However, it may be
possible to use some of the methods in this Technical Report to evaluate multiple exposures when some of the
sources are not designed to radiate EM energy, e.g. microwave ovens or RF welders and dryers.
This Technical Report establishes basic, rigorous techniques to estimate accurately and
conservatively the combined exposure from multiple EM sources. In developing International
Standards, it is anticipated that IEC Project Teams may deviate from or further evolve these
techniques as required to better address specific device or evaluation requirements.
The techniques established in this Technical Report allow summing internal fields for the
purpose of determining SAR and external fields for determining the power density. They do
not describe how to perform the volume or surface averaging procedures that would be
required to derive the compliance metrics (e.g., 10-g SAR or spatially-averaged power density)
most commonly employed in national or international exposure guidelines.
This Technical Report does not define any test method or algorithm to determine product
compliance with exposure limits, leaving that task to product compliance standards. Even
though an effort is made to provide guidance consistent with the most referenced international
exposure guidelines, the Technical Report does not establish or imply any requirement to
follow any specific national or international exposure guideline since that is a regulatory
matter. Rather, imposition of requirements depends on the policy of national regulators.

TR 62630 © IEC:2010(E) – 7 –
GUIDANCE FOR EVALUATING EXPOSURE
FROM MULTIPLE ELECTROMAGNETIC SOURCES

1 Scope
This Technical Report describes exposure evaluation concepts and techniques for the overall
exposure level in spatial regions and occupants caused by the simultaneous exposure to
multiple narrowband electromagnetic (EM) sources. Throughout this Technical Report, it is
assumed that the exposure evaluation occurs under static conditions, i.e., the source position
and transmit-mode characteristics (e.g. emitted power, modulation scheme, etc.) of the
device(s) under test do not vary significantly over the time required to carry out the evaluation
using the chosen evaluation technique (e.g., field measurements).
The vast majority of wireless communication systems worldwide employ signalling schemes
featuring narrowband waveforms, hereinafter defined as signal waveforms occupying a
frequency band not broader than 10 % of its central frequency (justification of this threshold is
provided below). For information, Annex A presents the operating system bands and channel
bandwidths of several common wireless services.
Wide-band communication systems, e.g., ultra-wideband (UWB) systems employing impulsive
waveforms with fractional bandwidth well in excess of 10 %, are relatively new to the
marketplace, have experienced limited deployment so far, and are not typically regarded as
significant contributors to EM exposure levels due to low transmit power levels.
NOTE Present exposure evaluation standards for fixed or mobile wireless communication devices, e.g.,
IEC 62209-1, are mostly tailored towards defining suitable techniques for narrowband waveforms. For instance,
they recommend the use of scalar E-field or H-field sensors, e.g., miniature diode-detector probes, which typically
provide accurate readings for narrowband waveforms, as defined herein. The paucity of UWB wireless
communication systems, which have only very recently been introduced in the marketplace, as well as the low
power levels associated with the corresponding signals to avoid interfering with coexisting electronic systems, has
so far reduced the priority to standardize suitable evaluation techniques and to develop the relevant test
instrumentation.
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.
IEC 62209-1:2005, Human exposure to radio frequency fields from handheld and body-
mounted wireless communication devices – Human models, instrumentation, and
procedures – Part 1: Procedure to determine the specific absorption rate (SAR) for hand-held
devices used in close proximity to the ear (frequency range of 300 MHz to 3 GHz)

– 8 – TR 62630 © IEC:2010(E)
3 Terms, definitions and abbreviations
For the purposes of this document, the following terms and definitions apply.
3.1 Terms and definitions
3.1.1
air-interface
access mode
the radio portion of the link between the mobile station and the active base station. In the
context of the Open Systems Interconnection Reference Model, the air interface operates at
the Physical Layer and the Data Link Layer
3.1.2
antenna
aerial (deprecated)
that part of a radio transmitting or receiving system which is designed to provide the required
coupling between a transmitter or a receiver and the medium in which the radio wave
propagates
NOTE 1 In practice, the terminals of the antenna or the points to be considered as the interface between the
antenna and the transmitter or receiver should be specified.
NOTE 2 If a transmitter or receiver is connected to its antenna by a feed line, the antenna may be considered to
be a transducer between the guided waves of the feed line and the radiated waves in space.
3.1.3
antenna array
an antenna comprised of a number of generally identical radiating elements, arranged,
oriented and excited to obtain a prescribed radiation pattern enhancing radiation in one or
more directions and reducing radiation in other directions
NOTE 1 Typical examples include vertical arrays used in panel antennas at RBS sites.
NOTE 2 In most cases radiating elements are identical and congruent by translation or by rotation about an axis;
moreover they are in general regularly spaced.
NOTE 3 In French, unless otherwise specified, the use of the term "antenne en réseau" implies that radiating
elements are congruent by a simple translation.
3.1.4
antenna array, adaptive
smart antenna
antenna system incorporating active circuits associated with radiating elements whereby one
or more of the characteristics of the antenna are automatically modified in a prescribed
manner as a function of the received signal or changes in the electromagnetic environment
NOTE Recently, the technology has been extended to use the multiple antennas at both the transmitter and
receiver; such a system is called a multiple-input multiple-output (MIMO) system. As extended smart antenna
technology, MIMO supports spatial information processing, which includes spatial information coding such as
Spatial Multiplexing and Diversity Coding, as well as beamforming.
3.1.5
antenna field regions
classification of the important spatial subdivisions of an antenna electromagnetic field. The
subdivisions, at non-uniquely defined distances from the antenna, include the reactive near-
field region adjacent to the antenna, the radiating near-field region (for large antennas
commonly referred to as the Fresnel region), a transition zone, and furthermost, the far-field
region, also known as the Fraunhofer region. See also: near-field region and far-field region

TR 62630 © IEC:2010(E) – 9 –
3.1.6
antenna gain
ratio, generally expressed in decibels, of the radiation intensity produced by an antenna in a
given direction to the radiation intensity that would be obtained if the power accepted by the
antenna were radiated equally in all directions
NOTE 1 If no direction is specified, the direction of maximum radiation intensity from the given antenna is implied.
NOTE 2 If the antenna is lossless, its absolute gain is equal to its directivity in the same direction.
3.1.7
antenna, radiation pattern
spatial distribution of a quantity that characterizes the electromagnetic fields radiated by an
antenna
NOTE The distribution can be expressed as a mathematical function or as a graphic representation. The
quantities that are most often used to characterize the radiation from an antenna are proportional to, or equal to,
power density, radiation intensity, directivity, phase, polarisation, and field strength.
3.1.8
antenna, reconfigurable beam
shaped-beam antenna designed so that some of its radiation characteristics, such as the
radiation pattern, can easily be modified, for example by telecommand
3.1.9
antenna, steerable-beam
antenna in which the direction of the main lobe can be changed either by controlling the
excitation of the different elements or by mechanical means other than moving the entire
antenna
3.1.10
average (temporal) power
ΔT , given by
rate of radiated energy transfer over a given time interval
tT+Δ /2
Pt = Pττd ,
() ()
avg
∫
ΔT
tT−Δ /2
where
ΔT is the (sliding) observation time window in seconds;
P t is the instantaneous transmitted power in watts;
()
P is the average (temporal) transmitted power over the interval ΔT in watts
avg
NOTE The average power is a function of the time window ΔT , assuming a constant value only if ΔT →∞ .
3.1.11
average (temporal) power density
instantaneous power density integrated over a specific time duration. The time duration could
be source related, e.g., the source repetition period, or use related, e.g., the averaging time
specified in exposure guidelines. Average power density is expressed in units of watts per
square metre (W/m )
NOTE In speaking of average power density in general, it is necessary to distinguish between the spatial average
(at a given instant) and the time average (at a given point).

– 10 – TR 62630 © IEC:2010(E)
3.1.12
basic restriction
restrictions on human exposure to time-varying electric, magnetic, and electromagnetic fields
that are based directly on the applicable national or international exposure guidelines
NOTE In the context of this Technical Report, applicable specific absorption rate (SAR) limits represent the basic
restrictions.
3.1.13
beamforming (digital)
method used to create the radiation pattern of the antenna array by adding constructively the
phases of the signals in the direction of the targets/mobiles desired, and nulling the pattern of
the targets/mobiles that are undesired/interfering targets. This may be done adaptively by
digital signal processors to provide optimal beamforming
3.1.14
co-located transmitters
transmitters located in close proximity to each other so they can be considered as occupying
the same location
NOTE The distance under which two or more transmitters may be considered as “co-located” depends on their
respective power and frequency, as well as on the evaluation area or volume of interest. “Co-location”, a property
describing in general the relative proximity of two or more objects, i.e. occupying together a single location, may
have impact on the approach required to evaluate the overall exposure.
3.1.15
collinear array
an antenna consisting of a linear array of radiating elements, usually dipoles, with their axes
lying in a straight line
3.1.16
complex (electric or magnetic) field envelope
a complex vector whose components are the complex envelopes of the electric or magnetic
field components. For time-harmonic fields, the complex envelope reduces to the field phasor
3.1.17
conductivity, (equivalent electrical)
scalar or tensor quantity the product of which by the electric field strength in a medium is
equal to the electric current density. The unit of conductivity is siemens per metre (S/m)
NOTE For an isotropic medium the conductivity is a scalar quantity; for an anisotropic medium it is a tensor
quantity.
3.1.18
correlated waveforms (in time)
signal waveforms yielding non-zero time-domain correlation integral at some time instant. For
two power-limited signals s ()ts, ()t , said integral is defined as
+T
+
()s⊗=st() s()ττs (t+ )dτ ,
lim ∫
12 1 2
2T
T→∞
−T
where the superscript + represents the complex conjugate operation.
NOTE This definition is mathematically convenient since it allows exploiting some useful analytical properties of
correlation and convolution integrals but requires knowledge of the signal waveforms over an infinite time. Such a
requirement may be impractical when performing exposure measurements. As discussed in Annex B, B.2 and B.3,
when dealing with wireless communication waveforms that typically feature very large bit-rates due to high data
throughputs and processing gains, signal correlation may be accurately characterized over a few seconds at most.

TR 62630 © IEC:2010(E) – 11 –
3.1.19
correlated fields (in time)
electromagnetic fields, associated to distinct signal waveforms, yielding non-zero time-domain
correlation integral at some time instant. For two power-limited field distributions
Fr(,tt),F (,r ) , said integral is defined as
+T
+
()FF⊗=(r,,tt) F()rττ⋅F(r,+)dτ ,
lim ∫
12 1 2
2T
T→∞
−T
where r is the location vector and the symbol ⋅ represents the inner product operation.
NOTE Observe that two fields are uncorrelated at locations where they are geometrically orthogonal. This
property does not generally hold at nearby points unless the respective waveforms are uncorrelated (Annex B, B.2).
3.1.20
device
material element or assembly of such elements intended to perform a required function
NOTE In the context of this Technical Report, a device may comprise multiple EM sources.
3.1.21
dipole antenna
doublet
a symmetrical antenna composed of conductors usually rectilinear and energized by a
balanced feed
NOTE The word "dipole" is sometimes used to describe antennas which do not conform in all respects to the
above definition. In such cases, the word should be qualified, for example: "asymmetrical dipole". Common usage
considers a dipole antenna to be a metal radiating structure that supports a line-current distribution similar to that
of a thin straight wire, a half-wavelength long, so energized that the current has a node only at each end.
3.1.22
electric field strength
vector field quantity E which exerts on any charged particle at rest a force F equal to the
product of E and the electric charge q of the particle
FE= q ,
where
F is the vector force acting on the particle in newtons;
q  is the charge on the particle in coulombs;
E is the electric field in volts per metre.
3.1.23
(plane-wave) equivalent power density
the normalised value of the square of the electric or the magnetic field strength at a point. The
value is expressed in W/m and is computed in terms of the electric or magnetic field as
follows:
||E
rms
S==η||H
0 rms
η
– 12 – TR 62630 © IEC:2010(E)
where η is the free space wave impedance, approximately 377 Ω.
3.1.24
exposure evaluation
process of measuring or estimating the intensity, frequency (and duration of human exposure
if required to compare with applicable exposure limits), field strength, power density or SAR
associated with electromagnetic fields
3.1.25
exposure, partial-body
localised exposure of part of the body, producing a corresponding localised SAR, as distinct
from a whole-body exposure
3.1.26
exposure, whole-body
exposure of the whole body
3.1.27
exposure quotient (EQ)
the evaluated exposure parameter related to the relevant compliance limit expressed as the
energy-intensive fraction of the related limit at a given frequency
3.1.28
far-field region
that region of the time-harmonic 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 spherical-wave character and, locally, a substantial plane-wave
character, i.e., very uniform distributions of electric field strength and magnetic field strength
in planes transverse to the direction of propagation. For larger antennas especially, the far-
field region is also referred to as the Fraunhofer region
3.1.29
intended use
the reasonably foreseeable use of a device for the purpose intended, over its full range of
applicable functions, in accordance with the instructions provided by the manufacturer,
including instructions on installation, operating position and orientation
3.1.30
isotropic field sensor (probe)
electric field or magnetic field sensor whose response is independent of the polarisation and
incidence angle of the incident waves
3.1.31
magnetic field strength
vector quantity H obtained at a given point by subtracting the magnetisation M from the
magnetic flux density B divided by the magnetic constant μ :
B
HM=−
μ
where
B is the magnetic flux density in teslas; a vector field quantity which exerts on
any charged particle q having velocity v a force Fv=×q B ;
()
TR 62630 © IEC:2010(E) – 13 –
μ is the magnetic constant (permeability) in henries per metre;
M is the magnetisation in amperes per metre; for the purposes of this document,
we shall assume M0= in exposed tissues and in air;
H is the magnetic field in amperes per metre
3.1.32
multiple-input and multiple-output (MIMO)
the use of multiple antennas at both the transmitter and receiver to improve communication
performance. It is one of several forms of smart antenna technology
3.1.33
multi-band (transmitter or device)
a transmitter or device capable of operating in more than one frequency band
3.1.34
multi-mode (transmitter or device)
a transmitter or wireless device capable of operating in more than one air-interface, e.g.,
UMTS, GSM and WLAN
3.1.35
narrowband electromagnetic source
source of electromagnetic field emissions whose occupied bandwidth is 10 % or less than its
centre frequency
NOTE The terms narrowband, broadband, ultra-wideband have been used with different meanings and
interpretations for different wireless products, technologies and markets. Therefore, the present definition is
explicitly intended to be applicable within the context of this Technical Report.
3.1.36
near-field region
a region in the time-harmonic field of an antenna, located near the antenna, in which the
electric and magnetic fields do not have a substantially plane-wave character, but vary
considerably from point to point
NOTE The term is only vaguely defined and has different meanings for large and small antennas. It is further
subdivided into the reactive near-field region, which is closest to the antenna and contains most or nearly all of the
stored energy associated with the field of the antenna, and the radiating near-field region. If the antenna has a
maximum overall dimension that is not large compared with the wavelength, the radiating near-field region may not
exist. For antennas large in terms of wavelength, the radiating near-field region is sometimes referred to as the
Fresnel region on the basis of analogy to optical terminology.
3.1.37
occupied bandwidth
width of the occupied band of an emission
3.1.38
peak spatial-average SAR
the maximal value of the local SAR averaged over a specified volume or mass, e.g., any 1 g
or 10 g of tissue in the shape of a cube. SAR is expressed in units of watts per kilogram
(W/kg)
3.1.39
phantom, (head or torso)
in the context of this Technical Report, a simplified representation or a model similar in
appearance to the human (head or torso) anatomy and composed of materials with electrical
properties similar to the corresponding tissues

– 14 – TR 62630 © IEC:2010(E)
3.1.40
point source
source of radiation the dimensions of which are small enough, compared with the distance
between the source and the irradiated surface, for them to be neglected in calculations and
measurements
NOTE A point source which emits uniformly in all directions is called an isotropic or uniform point source.
3.1.41
polarisation (of a wave or field vector)
the property of a sinusoidal electromagnetic wave or field vector defined at a fixed point in
space by the direction of the electric field strength vector or of any specified field vector;
when this direction varies with time the property may be characterized by the locus described
by the extremity of the considered field vector
3.1.42
power
a physical quantity describing the rate of delivery or transmission of energy. In this document,
power will refer to radio frequency power with units of watts (W)
3.1.43
power (flux) density
the power passing through an element of surface normal to the direction of propagation of
energy of an electromagnetic wave divided by the area of the element, usually expressed in
watts per metre squared (W/m ). Also referred to as radiant flux density
3.1.44
radio communication base station (RBS)
fixed equipment including the radio transmitter and associated antenna(s) as used in wireless
telecommunications networks
3.1.45
radio frequency (RF)
the frequency in the portion of the electromagnetic spectrum that is between the audio-
frequency portion and the infrared portion
NOTE The present practicable limits of radio frequency are roughly 10 kHz–300 GHz. Within this frequency range,
electromagnetic radiation may be detected and amplified as an electric current at the wave frequency.
3.1.46
reactive field
electric and magnetic fields surrounding an antenna or other electromagnetic devices that
result in storage rather than propagation of electromagnetic energy
3.1.47
root-mean-square (r.m.s.) value
for a time-dependent quantity, positive square root of the mean value of the square of the
quantity taken over a given time interval ΔT . Also referred to as effective value. For a
complex quantity z depending on a real variable t, the r.m.s. value of the magnitude of z is:
tT+Δ /2
ztz= ττd .
() ()
rms ∫
rms
ΔT
tT−Δ /2
NOTE 1 For a periodic quantity, the time interval comprises an integral number of periods.
NOTE 2 For a sinusoidal quantity A cos(ω t + θ), the r.m.s. value is A/ √2.

TR 62630 © IEC:2010(E) – 15 –
3.1.48
scalar field sensor (probe)
in the context of this Technical Report, an isotropic probe providing readings of the magnitude
of the field components, or a single reading of the field magnitude
3.1.49
source, electromagnetic (EM)
in the context of this Technical Report, the ensemble of physical transducers (e.g., RF mixers,
transmission lines, power amplifiers, filters, antennas) inside a wireless communication device
that transpose a suitably encoded and modulated signal carrying communication information
into radiated EM waves emanating from the device. Also referred to as transmitter
3.1.50
spatial average
as applied to the measurement of electric or magnetic fields for the assessment of whole-body
exposure means the root mean square of the field over a suitably defined area. The spatial
average can be measured by scanning a suitable measurement probe
3.1.51
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
( ρ ):
⎛⎞
ddW d dW
⎛⎞
SAR== .
⎜⎟ ⎜⎟
dt dm dt ρdV
⎝⎠
⎝⎠
SAR can be obtained using the following expression:
σ
SAR = ||E ,
rms
ρ
where
||E is the r.m.s. value of the electric field strength in the tissue in volts per metre;
rms
σ is the electric conductivity of the tissue in siemens per metre;
ρ is the density of the tissue in kilograms per cubic metre;

SAR is the specific absorption rate in watts per kilogram.
3.1.52
vector field sensor (probe)
in the context of this Technical Report, an isotropic probe providing readings of the magnitude
and the phase for each the field component
3.1.53
wavelength
distance in the direction of propagation of a periodic wave between two successive points at
which the phase is the same. The wavelength λ is related to the magnitude of the phase
velocity v and the frequency f by the equation:
p
– 16 – TR 62630 © IEC:2010(E)
v
p
λ = .
f
The wavelength λ of an electromagnetic wave is related to the frequency and speed of light
in the medium by the expression:
cf= λ ,
where:
f is the frequency in hertz;
c is the speed of light in metres per second;
λ is the wavelength in metres.
NOTE In free space the velocity of an electromagnetic wave is equal to the speed of light in vacuo. The
wavelength in a medium is equal to the wavelength in vacuo divided by the refractive index of the medium. Unless
otherwise stated, values of wavelength are generally those in air.
3.2 Physical quantities
The internationally accepted SI-units are used throughout this Technical Report.
Symbol Quantity Unit Dimensions
–1
E electric field strength volt per metre V m
f frequency hertz Hz
–1
H magnetic field strength ampere per metre A m
P
average (temporal) power watt W
avg
–1
SAR specific absorption rate watt per kilogram W kg
–2
S (plane-wave) equivalent power density Watt per square metre W m
–1
ε dielectric permittivity farad per metre F m

λ wavelength metre m
–1
μ magnetic permeability henry per metre H m
–3
ρ mass density kilogram per cubic metre Kg m
–1
(equivalent) electrical conductivity siemens per metre S m

σ
3.3 Constants
Symbol Physical constant Magnitude
8 –1
c
speed of light in vacuo 2,9979 × 10 m s
η impedance of free space 376,73 Ω
–12 –1
permittivity of free space
ε 8,8542 × 10 F m
–7 –1
permeability of free space
μ 4 π × 10 H m
3.4 Abbreviations
(N)AMPS (Narrowband) Advanced Mobile Phone System
BCCH Broadcast Control Channel
CDMA Code Division Multiple Access
D-AMPS Digital Advanced Mobile Phone System
DECT Digital Enhanced Cordless Telecommunications

TR 62630 © IEC:2010(E) – 17 –
EM  Electromagnetic
FDTD Finite-Difference Time-Domain
FEM Finite Element Method
GSM Global System for Mobile communications (originally Groupe Spécial Mobile)
JTACS Japanese Total Access Communication System
LTE Long Term Evolution
MIMO Multiple-Input and Multiple-Output
MoM Method of Moments
NFC Near Field Communication
PDC Personal Digital Cellular
PHS Personal Handy-phone System
RBS Radio Communication Base Station
RF  Radio Frequency
r.m.s., rms Root Mean Square
SAR Specific Absorption Rate
(E)TACS (Extended) Total Access Communication System
TETRA Trans-European Trunked RAdio
UMTS Universal Mobile Telecommunications System
UWB Ultra Wide Band
Wi-Fi Wireless Fidelity
WiMAX Worldwide Inter-operability for Microwave Access
WLAN Wireless Local Area Network
TV  Television
3.5 Vector notations
Throughout this Technical Report, space-time domain vectors are indicated by lowercase bold
symbols (e.g., er(,t) for the electric field) and the relative complex envelopes by uppercase
bold characters (e.g., Er(,t) ). The corresponding components are indicated by italicized
lowercase (e.g., et(,r ),w =x,y,z ) and uppercase (e.g., E (,r t) ) symbols, respectively.
w w
4 Overview
Exposure from multiple EM sources is quite common, particularly in the case of simultaneous
exposure from multiple broadcast and cellular infrastructure transmitters. For instance, urban
and suburban areas are typically covered by broadcast services, e.g., radio and TV, as well
as by mobile communication services, e.g., mobile telephony, public safety and emergency
systems. Exposure levels from these kinds of sources, at locations where people would
normally reside, are typically orders of magnitude lower than the main international exposure
guideline limits. The respective frequency bands are typically disjointed, thus the
corresponding signal waveforms are uncorrelated (see Subclause 6.2), and the overall
exposure may be readily determined by a suitable summation of the individual exposure
contributions expressed in terms of energy-intensive quantities, e.g., power density.
Over the last few years combined data and voice communication systems, e.g., UMTS and
WiMAX, have been deployed. There is also a growing number of personal communication
devices that allow simultaneous transmission over multiple air-interfaces while being operated
near the user’s body. In most cases, multiple transmitters in portable wireless communicators
operate in distinct frequency bands, e.g., GSM and Bluetooth, so the overall exposure can be
determined by summing the corresponding SAR distributions. SAR summation is also
...