Determining the peak spatial-average specific absorption rate (SAR) in the human body from wireless communication devices, 30 MHz to 6 GHz - Part 4: General requirements for using the finite element method for SAR calculations

IEC/IEEE 62704-4:2020 describes the concepts, techniques, and limitations of the finite element method (FEM) and specifies models and procedures for verification, validation and uncertainty assessment for the FEM when used for determining the peak spatial-average specific absorption rate (psSAR) in phantoms or anatomical models. It recommends and provides guidance on the modelling of wireless communication devices, and provides benchmark data for simulating the SAR in such phantoms or models.
This document does not recommend specific SAR limits because these are found elsewhere (e.g. in IEEE Std C95.1 or in the guidelines published by the International Commission on Non-Ionizing Radiation Protection (ICNIRP)).
This publication is published as an IEC/IEEE Dual Logo standard.

Détermination du débit d'absorption spécifique (DAS) maximal moyenné dans le corps humain, produit par les dispositifs de communications sans fil, 30 MHz à 6 GHz - Partie 4: Exigences générales d'utilisation de la méthode des éléments finis (FEM) pour les calculs du DAS

IEC/IEEE 62704-4:2020 décrit les concepts, techniques et limitations de la méthode des éléments finis (FEM – finite-element method) et spécifie les modèles et procédures de vérification, de validation et d'évaluation de l'incertitude de cette méthode FEM lorsqu'elle est utilisée pour déterminer le débit d'absorption spécifique maximal moyenné (psSAR) dans les fantômes ou les modèles anatomiques. Le présent document recommande et donne des recommandations en matière de modélisation des dispositifs de communications sans fil, et fournit les données de référence pour la simulation du DAS dans ce type de fantômes ou de modèles.
Le présent document ne recommande aucune limite de DAS particulière étant donné qu'elles sont définies dans d'autres normes (dans la norme IEEE C95.1 ou dans les lignes directrices publiées par l'ICNIRP (International Commission on Non-Ionizing Radiation Protection – Commission internationale sur la protection contre les rayonnements non ionisants) par exemple).
Cette publication est publiée sous la forme d’une norme IEC/IEEE Dual Logo.

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IEC/IEEE 62704-4
Edition 1.0 2020-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Determining the peak spatial-average specific absorption rate (SAR) in the
human body from wireless communication devices, 30 MHz to 6 GHz –
Part 4: General requirements for using the finite element method for SAR
calculations
Détermination du débit d’absorption spécifique (DAS) maximal moyenné
dans le corps humain, produit par les dispositifs de communications sans fil,
30 MHz à 6 GHz –
Partie 4: Exigences générales d'utilisation de la méthode des éléments finis
pour les calculs du DAS
IEC/IEEE 62704-4:2020-10(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC/IEEE 62704-4
Edition 1.0 2020-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Determining the peak spatial-average specific absorption rate (SAR) in the
human body from wireless communication devices, 30 MHz to 6 GHz –
Part 4: General requirements for using the finite element method for SAR
calculations
Détermination du débit d’absorption spécifique (DAS) maximal moyenné
dans le corps humain, produit par les dispositifs de communications sans fil,
30 MHz à 6 GHz –
Partie 4: Exigences générales d'utilisation de la méthode des éléments finis
pour les calculs du DAS
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.220.20 ISBN 978-2-8322-8535-0

Warning! Make sure that you obtained this publication from an authorized distributor.

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® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – IEC/IEEE 62704-4:2020 © IEC/IEEE 2020
CONTENTS

FOREWORD ........................................................................................................................... 5

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

1 Scope .............................................................................................................................. 8

2 Normative references ...................................................................................................... 8

3 Terms and definitions ...................................................................................................... 8

4 Abbreviated terms ........................................................................................................... 9

5 Finite element method – basic description ....................................................................... 9

6 SAR calculation and averaging ...................................................................................... 10

6.1 General ................................................................................................................. 10

6.2 SAR averaging ...................................................................................................... 11

6.2.1 General ......................................................................................................... 11

6.2.2 Evaluation of psSAR with an FEM mesh ........................................................ 11

6.3 Power scaling ....................................................................................................... 12

7 Considerations for the uncertainty evaluation ................................................................ 12

7.1 General ................................................................................................................. 12

7.2 Uncertainty due to device positioning, mesh density, and simulation

parameters ........................................................................................................... 13

7.2.1 General ......................................................................................................... 13

7.2.2 Mesh convergence......................................................................................... 14

7.2.3 Open boundary conditions ............................................................................. 14

7.2.4 Power budget ................................................................................................ 14

7.2.5 Convergence of psSAR sampling ................................................................... 14

7.2.6 Dielectric parameters of the phantom or body model ..................................... 15

7.3 Uncertainty and validation of the developed numerical model of the DUT .............. 15

7.3.1 General ......................................................................................................... 15

7.3.2 Uncertainty of the DUT model (d ≥ λ/2 or d ≥ 200 mm) ................................... 16

7.3.3 Uncertainty of the DUT model (d < λ/2 and d < 200 mm) ................................. 17

7.3.4 Phantom uncertainty (d < λ/2 and d < 200 mm) ............................................... 18

7.3.5 Model validation ............................................................................................ 19

7.4 Uncertainty budget ................................................................................................ 19

8 Code verification............................................................................................................ 20

8.1 General ................................................................................................................. 20

8.1.1 Rationale ....................................................................................................... 20

8.1.2 Code performance verification ....................................................................... 21

8.1.3 Canonical benchmarks .................................................................................. 21

8.2 Code performance verification .............................................................................. 21

8.2.1 Propagation in a rectangular waveguide ........................................................ 21

8.2.2 Planar dielectric boundaries .......................................................................... 26

8.2.3 Open boundary conditions ............................................................................. 28

8.3 Weak patch test .................................................................................................... 28

8.3.1 General ......................................................................................................... 28

8.3.2 Free-space weak patch test ........................................................................... 29

8.3.3 Dielectric-layer weak patch test ..................................................................... 33

8.4 Verification of the psSAR calculation .................................................................... 36

8.5 Canonical benchmarks .......................................................................................... 36

8.5.1 Mie sphere .................................................................................................... 36

---------------------- Page: 4 ----------------------
IEC/IEEE 62704-4:2020 © IEC/IEEE 2020 – 3 –

8.5.2 Generic dipole ............................................................................................... 37

8.5.3 Microstrip terminated with open boundary conditions ..................................... 38

8.5.4 psSAR calculation SAM phantom / generic phone .......................................... 39

8.5.5 Setup for system performance check ............................................................. 39

Annex A (informative) Fundamentals of the finite element method ....................................... 41

A.1 General ................................................................................................................. 41

A.2 Model boundary value problem ............................................................................. 41

A.3 Galerkin weak form ............................................................................................... 42

A.4 Finite element approximation ................................................................................ 42

A.5 Considerations for using FEM ............................................................................... 43

Annex B (informative) File format for field and SAR data...................................................... 44

Annex C (informative) Analytical solution for error calculation in weak patch-test

problems ............................................................................................................................... 45

C.1 Generation of control mesh and FEM field values ................................................. 45

C.2 Free-space weak patch test .................................................................................. 45

C.3 Dielectric-layer weak patch test ............................................................................ 45

Bibliography .......................................................................................................................... 48

Figure 1 – Waveguide filled half with free-space (green) and half with dielectric (blue) ......... 24

Figure 2 – Aligned rectangular waveguide and locations of the sample points E , E ,

01 10

E , E and E at which the E components are recorded ................................................ 25

11 12 21 x
Figure 3 – Weak patch test arrangement: a free-space cube with edge length L

illuminated by a plane wave .................................................................................................. 29

Figure 4 – Dielectric-layer weak patch test arrangement ....................................................... 33

Figure 5 – Geometry of the microstrip line ............................................................................ 38

Figure 6 – Geometry of the setup for the system performance check according to [21] ......... 40

Table 1 – Budget of the uncertainty contributions of the numerical algorithm and of the

rendering of the test-setup or simulation-setup ..................................................................... 13

Table 2 – Budget of the uncertainty of the developed model of the DUT................................ 17

Table 3 – Overall assessment uncertainty budget for the numerical simulation results .......... 20

Table 4 – Results of the evaluation of the numerical dispersion characteristics to be

reported for each mesh axis and each orientation of the waveguide for at least three

increasing numbers of DoF ................................................................................................... 25

Table 5 – Results of the evaluation of the numerical reflection coefficient to be

reported; frequency range is indicated for each value to be reported .................................... 27

Table 6 – Guiding parameters for coarse and fine mesh generation for the weak patch test .. 30

Table 7 – Results of the evaluation of the error measures on the control mesh for the

weak patch test for the lowest order ...................................................................................... 32

Table 8 – Results of the evaluation of the error measures on the control mesh for the

weak patch test for the second lowest order ......................................................................... 32

Table 9 – Results of the evaluation of the error measures on the control mesh for the

weak patch test for the third lowest order .............................................................................. 33

Table 10 – Guiding parameters for coarse and fine mesh generation for the dielectric-

layered weak patch test ........................................................................................................ 34

Table 11 – Results of the evaluation of error measures on the control mesh for the

dielectric-layered weak patch test for the lowest order .......................................................... 35

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– 4 – IEC/IEEE 62704-4:2020 © IEC/IEEE 2020

Table 12 – Results of the evaluation of error measures on the control mesh for the

dielectric-layered weak patch test for the second lowest order .............................................. 35

Table 13 – Results of the evaluation of error measures on the control mesh for the

dielectric-layered weak patch test for the third lowest order .................................................. 36

Table 14 – Results of the SAR evaluation of the Mie sphere ................................................. 37

Table 15 – Results of the dipole evaluation ........................................................................... 38

Table 16 – Results of the microstrip evaluation ..................................................................... 39

Table 17 – 1 g and 10 g psSAR for the SAM phantom exposed to the generic phone for

1 W accepted power as specified in [19] ............................................................................... 39

Table 18 – Dielectric parameters of the setup (Table 1 of [21]) ............................................. 40

Table 19 – Mechanical parameters of the setup (Tables 1 and 2 of [21]) ............................... 40

Table 20 – 1 g and 10 g psSAR normalized to 1 W accepted power and feed-point

impedance (Table 3 and Table 4 of [21]) ............................................................................... 40

---------------------- Page: 6 ----------------------
IEC/IEEE 62704-4:2020 © IEC/IEEE 2020 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
DETERMINING THE PEAK SPATIAL-AVERAGE SPECIFIC ABSORPTION
RATE (SAR) IN THE HUMAN BODY FROM WIRELESS
COMMUNICATION DEVICES, 30 MHZ TO 6 GHZ –
Part 4: General requirements for using the
finite element method for SAR calculations
FOREWORD

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---------------------- Page: 7 ----------------------
– 6 – IEC/IEEE 62704-4:2020 © IEC/IEEE 2020

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International Standard IEC/IEEE 62704-4 has been prepared by IEC technical committee

TC 106: Methods for the assessment of electric, magnetic and electromagnetic fields

associated with human exposure, in cooperation with International Committee on

Electromagnetic Safety of the IEEE Standards Association, under the IEC/IEEE Dual Logo

Agreement.
This publication is published as an IEC/IEEE Dual Logo standard.
The text of this standard is based on the following IEC documents:
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A list of all parts in the IEC/IEEE 62704 series, published under the general title Determining

the peak spatial-average specific absorption rate (SAR) in the human body from wireless

communications devices, 30 MHz to 6 GHz, can be found on the IEC website.

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---------------------- Page: 8 ----------------------
IEC/IEEE 62704-4:2020 © IEC/IEEE 2020 – 7 –
INTRODUCTION

Finite element methods have reached a level of maturity that allows their application in

specific absorption rate (SAR) assessments of professional-use and consumer-use wireless

communication devices. In the recent past, SAR compliance assessments for small
transmitters were performed almost exclusively using measurements. Some wireless

communication devices are used in situations where experimental SAR assessment is

extremely complex or not possible at all. National regulatory bodies (e.g. US Federal

Communications Commission) encourage the development of consensus standards and

encouraged the establishment of the ICES Technical Committee 34 Subcommittee 2. The

benefits to the users and the regulators include standardized and accepted protocols,

verification and validation techniques, benchmark data, reporting format and means for

estimating the overall assessment uncertainty in order to produce valid, repeatable, and

reproducible data.

The purpose of this document is to specify numerical techniques and models to determine

peak spatial-average specific absorption rates (SAR). SAR will be determined by applying

finite element method simulations of the electromagnetic field conditions produced by wireless

communication devices in models of the human anatomy. Intended users of this document are

(but are not limited to) wireless communication device manufacturers, service providers for

wireless communication that are required to certify that their products comply with the

applicable SAR limits, and government agencies.
Several methods described in this document are based on techniques specified in
IEC/IEEE 62704-1:2017.
---------------------- Page: 9 ----------------------
– 8 – IEC/IEEE 62704-4:2020 © IEC/IEEE 2020
DETERMINING THE PEAK SPATIAL-AVERAGE SPECIFIC ABSORPTION
RATE (SAR) IN THE HUMAN BODY FROM WIRELESS
COMMUNICATION DEVICES, 30 MHZ TO 6 GHZ –
Part 4: General requirements for using the
finite element method for SAR calculations
1 Scope

This part of IEC/IEEE 62704 describes the concepts, techniques, and limitations of the finite

element method (FEM) and specifies models and procedures for verification, validation and

uncertainty assessment for the FEM when used for determining the peak spatial-average

specific absorption rate (psSAR) in phantoms or anatomical models. It recommends and

provides guidance on the modelling of wireless communication devices, and provides

benchmark data for simulating the SAR in such phantoms or models.

This document does not recommend specific SAR limits because these are found elsewhere

(e.g. in IEEE Std C95.1 [1] or in the guidelines published by the International Commission on

Non-Ionizing Radiation Protection (ICNIRP) [2]).
2 Normative references

The following documents are referred to in the text in such a way that some or all of their

content constitutes requirements 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, Measurement procedure for the assessment of specific absorption rate of

human exposure to radio frequency fields from hand-held and body-mounted wireless

communication devices – Part 1: Devices used next to the ear (Frequency range of 300 MHz

to 6 GHz)

IEC/IEEE 62704-1:2017, Determining the peak spatial-average specific absorption rate (SAR)

in the human body from wireless communications devices, 30 MHz to 6 GHz – Part 1: General

requirements for using the finite-difference time-domain (FDTD) method for SAR calculations

IEEE Std 1528, IEEE Recommended Practice for Determining the Peak Spatial-Average

Specific Absorption Rate (SAR) in the Human Head From Wireless Communications Devices:

Measurement Techniques
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO, IEC, and IEEE maintain terminological databases for use in standardization at the

following addresses:
• IEC Electropedi
...

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