IEC TR 63377:2022
(Main)Procedures for the assessment of human exposure to electromagnetic fields from radiative wireless power transfer systems – Measurement and computational methods (frequency range of 30 MHz to 300 GHz)
Procedures for the assessment of human exposure to electromagnetic fields from radiative wireless power transfer systems – Measurement and computational methods (frequency range of 30 MHz to 300 GHz)
IEC TR 63377:2022 describes assessment methods to evaluate the compliance of radiative wireless power transfer (WPT) systems operating in the frequency range from 30 MHz to 300 GHz with electromagnetic guidelines on human exposure (electromagnetic field strength, specific absorption rate (SAR), and power density). This document includes but is not limited to systems that focus the electromagnetic energy emitted by the transmitter to regions surrounding the receiver, for example, by narrow beam-forming systems, wide-beam systems and spatially closed systems. Implementations without transmitter, for example, applications that harvest energy from the environment, are not included in the scope of this document.
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IEC TR 63377
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Edition 1.0 2022-11
TECHNICAL
REPORT
colour
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Procedures for the assessment of human exposure to electromagnetic fields
from radiative wireless power transfer systems – Measurement and
computational methods (frequency range of 30 MHz to 300 GHz)
IEC TR 63377:2022-11(en)
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IEC TR 63377
®
Edition 1.0 2022-11
TECHNICAL
REPORT
colour
inside
Procedures for the assessment of human exposure to electromagnetic fields
from radiative wireless power transfer systems – Measurement and
computational methods (frequency range of 30 MHz to 300 GHz)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 17.220.20, 33.050.10 ISBN 978-2-8322-5945-0
Warning! Make sure that you obtained this publication from an authorized distributor.
® Registered trademark of the International Electrotechnical Commission
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– 2 – IEC TR 63377:2022 © IEC 2022
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 8
4 Symbols and abbreviated terms . 10
4.1 Physical quantities . 10
4.2 Constants . 11
4.3 Abbreviated terms . 11
5 Description of radiative wireless power transfer systems . 12
5.1 General . 12
5.2 Radiative WPT systems technology and applications . 12
5.2.1 General . 12
5.2.2 Operating principle of space diversity WPT . 15
5.2.3 Operating principle of narrow-beam WPT. 16
5.3 Use cases and environment . 16
5.3.1 General . 16
5.3.2 Indoor, occupational environment . 16
5.3.3 Indoor, general-public environment . 18
5.3.4 Outdoor, occupational environment. 18
5.3.5 Outdoor, general-public environment . 19
6 General exposure assessment considerations . 19
6.1 General . 19
6.2 Preparation of assessment . 19
6.2.1 General . 19
6.2.2 Determination of key parameters . 19
6.2.3 Determination of applicable limits . 20
6.2.4 Determination of assessment method . 21
6.3 Assessment conditions . 23
6.4 Uncertainty . 23
Annex A (informative) Coupling factors and correction factors . 26
A.1 General . 26
A.2 Coupling factors for near-field exposure . 27
A.2.1 Characteristics of the near-field . 27
A.2.2 Coupling of electromagnetic energy in the near-field . 27
A.2.3 Considerations for whole-body exposure in the near-field . 27
A.2.4 Derivation of the coupling factors for E-field or H-field exposure . 27
A.3 Correction factors for far-field exposures . 28
A.3.1 Characteristics of the far-field . 28
A.3.2 Tissue layering . 28
A.3.3 Whole-body absorption and resonance . 29
A.3.4 Conservative correction factors . 29
A.4 Assessment of correction factors for layered tissues . 30
A.4.1 General . 30
A.4.2 Correction factors for peak-spatial average SAR . 30
A.4.3 Correction factors for whole-body SAR . 30
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IEC TR 63377:2022 © IEC 2022 – 3 –
A.4.4 Correction factors for partial body exposures . 30
A.4.5 Correction of SAR results in homogeneous flat phantoms . 31
Annex B (informative) Assessment procedure . 32
B.1 RF field strength and power density assessment for radiative WPT systems . 32
B.2 Local SAR assessment for radiative WPT systems operating between
30 MHz to 6 GHz . 32
B.2.1 General . 32
B.2.2 Preparation of the device under test . 33
B.2.3 Transmitter SAR assessment procedure . 33
B.2.4 Validation of the SAR assessment . 34
B.3 Incident power density (PD) assessment for local exposure over 6 GHz. 34
B.3.1 General . 34
B.3.2 Preparation of the device under test . 35
B.3.3 PD assessment procedure – Experimental only . 35
B.3.4 PD assessment procedure – Combined numerical and experimental
methods . 35
B.3.5 Validation of the assessment . 36
Annex C (informative) Description and validation of exposure mitigation techniques . 37
C.1 General . 37
C.2 Description of the technology and its implementation . 37
C.3 Validation of proximity sensors . 37
C.4 Validation of time-period power control . 38
C.5 System level validation of the exposure mitigation techniques . 38
Annex D (informative) Computational methods. 39
D.1 Methods and procedures . 39
D.2 Verification of the computational method . 39
D.3 Application of hybrid computational and experimental methods . 40
D.4 Considerations for the assessment of the numerical uncertainty . 40
D.4.1 General . 40
D.4.2 Parameters for the numerical uncertainty assessment . 40
Annex E (informative) Examples of exposure assessment . 41
E.1 Example of the dosimetric assessment of a WPT transmitter operating at
900 MHz . 41
E.1.1 Overview . 41
E.1.2 Method . 41
E.1.3 Model development and validation . 42
E.1.4 Dosimetric assessment of the anatomical models . 42
E.1.5 Results and conclusions . 43
E.2 Example E-field assessment of RF WPT system operating at 2,45 GHz . 43
E.2.1 General . 43
E.2.2 Assessment procedure . 44
E.2.3 E-field assessment results . 45
Bibliography . 50
Figure 1 – WPT system classification via radio-frequency beam technologies . 14
Figure 2 – Beam pattern diagram of omnidirectional radiative WPT. 15
Figure 3 – Beam pattern diagram of space diversity WPT . 15
Figure 4 – Beam pattern diagram of narrow-beam radiative WPT . 16
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– 4 – IEC TR 63377:2022 © IEC 2022
Figure 5 – Example of indoor and occupational environments: WPT to production
equipment sensors in factory . 17
Figure 6 – Example of indoor and occupational environments: WPT to machine and
line management sensors . 17
Figure 7 – WPT to children watching sensors . 18
Figure 8 – WPT to watching sensors in nursing homes . 18
Figure 9 – Assessment process for radiative WPT . 19
Figure B.1 – Flowchart for the SAR assessment procedure between 30 MHz to 6 GHz . 33
Figure B.2 – Description of PD assessment procedure between 6 GHz to 300 GHz . 35
Figure E.1 – Anatomical model of the five-year-old girl exposed to the WPT transmitter
E-field at a distance of 400 mm. The beam of the WPT system is focused at this
distance. . 43
Figure E.2 – E-field measurement setup of RF WPT system . 44
Figure E.3 – E-field measurement scenario and positioning of WPT source
(transmitter), client, and scan areas . 45
Figure E.4 – E-field distribution measured at the distance 20 cm from RF WPT
transmitter . 46
Figure E.5 – E-field distribution measured in the far-field zone of WPT source: a) at
the distance 2 m from RF WPT transmitter – in front of the client b) at the distance
2,75 m from RF WPT transmitter – behind the client . 46
Figure E.6 – E-field measurement scenario with the cylindrical phantom . 47
Figure E.7 – E-field measurement setup of RF WPT system with cylindrical phantom . 47
Figure E.8 – E-field distribution for the case of partial obstruction by the phantom: a)
14 cm and b) 8 cm distance from phantom outer surface to transmitter-client line . 48
Figure E.9 – E-field distribution measured in the horizontal plane within the distances
45 cm to 145 cm from transmitter antenna for the case of strong obstruction by the
phantom. The position of cylindrical phantom with respect to scan area is shown. . 49
Figure E.10 – E-field distribution measured at the distance 2,75 m from RF WPT
transmitter when cylindrical phantom is placed behind the client (case 3 in Figure E.6).
Field scan is performed between the client and phantom. . 49
Table 1 – Representative characteristics of potential radiative WPT applications . 13
Table 2 – Whole-body SAR exclusions based on RF power levels. 22
Table 3 – Template of measurement uncertainty budget for assessment of the psSAR
for frequencies from 30 MHz to 6 GHz . 24
Table 4 – Template of measurement uncertainty budget for assessment of the incident
power density for frequencies above 6 GHz . 25
Table A.1 – Summary of correction factors accounting for tissue layering effects
specified in IEC 62232:2017 [12] for psSAR and wbSAR. 29
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IEC TR 63377:2022 © IEC 2022 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PROCEDURES FOR THE ASSESSMENT OF HUMAN EXPOSURE TO
ELECTROMAGNETIC FIELDS FROM RADIATIVE WIRELESS POWER
TRANSFER SYSTEMS – MEASUREMENT AND COMPUTATIONAL
METHODS (FREQUENCY RANGE OF 30 MHz TO 300 GHz)
FOREWORD
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IEC TR 63377 has been prepared by IEC technical committee 106: Methods for the assessment
of electric, magnetic and electromagnetic fields associated with human exposure. It is a
Technical Report.
The text of this Technical Report is based on the following documents:
Draft Report on voting
106/568/DTR 106/578/RVDTR
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Technical Report is English.
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This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
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The committee has decided that the contents of this document will remain unchanged until the
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specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
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IMPORTANT – The "colour inside" logo on the cover page of this document indicates that it
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contents. Users should therefore print this document using a colour printer.
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IEC TR 63377:2022 © IEC 2022 – 7 –
INTRODUCTION
IEC TC 106 is tasked with preparing International Standards on measurement and simulation
methods used to assess human exposure to electric fields, magnetic fields, and electromagnetic
fields. Wireless power transfer (WPT) systems operating at 30 MHz to 300 GHz utilize electric
fields, magnetic fields, or electromagnetic fields to provide power to equipment nearby or at
distances up to several metres or more. Users or bystanders in close proximity to both the
transmitting equipment and receiving equipment or in between them could be exposed to these
fields. Assessment methods are needed to demonstrate compliance with applicable human
exposure limits. A working group (WG9) was established by IEC TC 106 to address assessment
methods of human exposure to WPT equipment.
This document consists of an overview of radiative WPT, exposure assessment methods,
procedures, and case studies, to help in the development of international standards for WPT
exposure assessment. This document addresses the frequency range of 30 MHz to 300 GHz.
For lower frequencies, WPT equipment operating below 10 MHz is covered by
IEC TR 62905:2018, and below 30 MHz is covered by IEC PAS 63184:2021, with an associated
subsequent International Standard currently under consideration by IEC TC 106. The methods
and procedures described in this document are based on the techniques of other exposure
standards covering the same frequency range. Other methods are referenced when deviations
from these assessment methods are needed.
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– 8 – IEC TR 63377:2022 © IEC 2022
PROCEDURES FOR THE ASSESSMENT OF HUMAN EXPOSURE TO
ELECTROMAGNETIC FIELDS FROM RADIATIVE WIRELESS POWER
TRANSFER SYSTEMS – MEASUREMENT AND COMPUTATIONAL
METHODS (FREQUENCY RANGE OF 30 MHz TO 300 GHz)
1 Scope
This Technical Report describes assessment methods to evaluate the compliance of radiative
wireless power transfer (WPT) systems operating in the frequency range from 30 MHz to
300 GHz with electromagnetic guidelines on human exposure (electromagnetic field strength,
specific absorption rate (SAR), and power density). This document includes but is not limited
to systems that focus the electromagnetic energy emitted by the transmitter to regions
surrounding the receiver, for example, by narrow beam-forming systems, wide-beam systems
and spatially closed systems. Implementations without transmitter, for example, applications
that harvest energy from the environment, are not included in the scope of this document.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
basic restriction
BR
human exposure limits for compliance with time-varying electric, magnetic, and electromagnetic
fields evaluated inside the body that are based on established adverse health effects
Note 1 to entry: Within the scope of this document, the physical quantity used as a basic restriction is the specific
absorption rate (SAR) or absorbed (epithelial) power density.
3.2
equipment under test
EUT
equipment that is tested according to the procedures described in this document
3.3
plane-wave equivalent power density
electromagnetic wave, magnitude of the power density of a plane wave having the same ratio
of electric (E) field strength to magnetic (H) field strength
2
Note 1 to entry: The SI unit of plane-wave equivalent power density is watt per square metre (W/m ).
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IEC TR 63377:2022 © IEC 2022 – 9 –
3.4
exposure
situation that occurs wherever a person is subjected to electric, magnetic, or
electromagnetic fields
3.5
far-field region
region of the electromagnetic field of an antenna wherein the predominant
components of the field are those which represent a propagation of energy and wherein the
angular field distribution is essentially independent of the distance from the antenna
[SOURCE: IEC 60050-712:1992 [1], 712-02-02, modified – Hyphen added to the term, notes to
entry omitted.]
3.6
incident field
field that would exist in the absence of a person over a volume where a person could be located
Note 1 to entry: In some documents, the incident field is called an unperturbed field or environmental field.
3.7
reactive near-field region
region of space immediately surrounding an antenna, where the predominant components of
the electric field and magnetic field are those that represent an exchange of reactive energy
between the antenna and the surrounding medium, and where the electric field and magnetic
field components are 90° out of phase
[SOURCE: IEC/IEEE 63195-1:2022 [2], 3.2.10, modified – The word "region" has been added
to the term.]
3.8
peak spatial-average SAR
psSAR
maximum SAR averaged within a local region based on a specific averaging mass, e.g. any 1 g
or 10 g of tissue in the shape of a cube
[SOURCE: IEC/IEEE 62209-1528:2020 [3], 3.37, modified – The note to entry has been
omitted.]
3.9
phantom
physical model with an equivalent human anatomy and comprised of a tissue-equivalent
medium with dielectric properties specified in IEC/IEEE 62209-1528:2020
[SOURCE IEC/IEEE 62209-1528 [3], 3.39, modified – The wording "in this document" is
replaced with "IEC/IEEE 62209-1528:2020".]
3.10
radiative wireless power transfer system
radiative WPT system
system that transfers power by radiation of electromagnetic energy from a transmitter to a
receiver in the frequency range from 30 MHz to 300 GHz
3.11
reference level
RL
level of field strength or power density derived from the basic restrictions using conservative
assumptions about exposure
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Note 1 to entry: If the reference levels are met, then the basic restrictions will be complied with, but if the reference
levels are exceeded, that does not necessarily mean that the basic restrictions will not be met.
[SOURCE IEC 62311:2019 [4], 3.1.22, modified – Abbreviated term "RL" added.]
3.12
specific absorption rate
SAR
measure of the rate at which energy is absorbed by the human body when exposed to a radio
frequency electromagnetic field
Note 1 to entry: The SAR in the tissue-equivalen
...
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