ENGLISH TRANSLATIONGUIDELINES FOR THE USE OFWIRELESS POWER TRANSMISSION/TRANSFERTECHNOLOGIESTECHNICAL REPORTBWF TR-01 Edition 2.0

Published in April 26, 2011
Revised in April 25, 2013

Broadband Wireless Forum Japan

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Preface
The Broadband Wireless Forum was established on July 3, 2009 to contribute to the sounddevelopment of new systems and services utilizing radio waves. The forum has been performing
various activities on wireless technologies, such as research, development and investigation of new
wireless technology, the collection of information, liaison and coordination with relatedorganizations, and dissemination and awareness-raising activities for the early realization andinternational expansion of systems and services using new wireless technology. One of the results ofthese activities, this technical information is compiled and released as a “technical report.”
This technical report is designed to specify a set of guidelines for the “use of wireless powertransmission/transfer technologies.” In states where we can expect the early practical application of
wireless power transmission/transfer technology due to its steady progress, this report will serve as a
guideline that product manufacturers and service providers applying such technology should bereferred in order to improve convenience for users and to guarantee the safety of such users.

We hope that these guidelines will be actively utilized by machine manufacturers, service providers,test institutes, and users.

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Contents
SectionPage

1. Scope ................................................................................................................................................5
2. Applicable regulations and normative references ........................................................................6
2.1 Applicable regulations ..............................................................................................................6
2.2 Normative references ................................................................................................................6
3. Definitions ........................................................................................................................................7
4. General requirement ..................................................................................................................... 11
5. General requirement for the tests ................................................................................................12
6. Classification .................................................................................................................................12
7. Marking and instructions .............................................................................................................14
8. Conditions for the use ...................................................................................................................15
8.1 Radio Acts referenced by these guidelines ............................................................................15
8.1.1 Requirements of high frequency-based equipment covered by these guidelines that
do not require permission.........................................................................................................15
8.2 Safety measures for equipment or systems using wireless power transmission/transfer
technologies....................................................................................................................................15
8.2.1 Basic safety measurements ..............................................................................................16
8.2.2 Safety measures specific to wireless power transmission/transfer ...............................16
8.2.2.1 Identification of reception sides and power transmission restrictions .........................16
8.2.2.2 Measures to prevent metal pieces located in the path of the power transmission linefrom overheating .....................................................................................................................16
8.2.2.3 Measures to prevent metal pieces located at the periphery of the power transmission
equipment (transmission equipment) or reception equipment from overheating ....................178.2.2.4 Safety measures to protect any human body that is located in the path, or at the
periphery, of the power transmission line ...............................................................................178.2.2.5 Safety measures for the case where a non-metal piece is located in the path of thepower transmission line ..........................................................................................................178.2.2.6 Safety measures for the location of reception equipment ...........................................178.2.2.7 Safety measures against abnormal operation during power transmission ...................18
8.2.3 Safety measures for other types of wireless power transmission/transfer equipment or
systems .......................................................................................................................................18
8.2.3.1 Safety measures for a wireless power transmission/transfer technology that operates
on microwave technology .......................................................................................................18
8.2.3.2 Safety measures for a wireless power transmission/transfer technology that operates
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on coupled electromagnetic field ............................................................................................18
8.3 Conformance to the radio-radiation protection guidelines .................................................18
8.3.1 Principles ..........................................................................................................................18
8.3.2 Evaluation items for electromagnetic field exposure by frequency range ..................19
8.3.2.1 [Frequency range A] Evaluation items for the electromagnetic field exposure in thefrequency range of 10 kHz to 100 kHz ...................................................................................20
8.3.2.2 [Frequency range B] Evaluation items for electromagnetic field exposure in thefrequency range of 100 kHz to 10 MHz..................................................................................218.3.2.3 [Frequency range C] Evaluation items for the electromagnetic field exposure in thefrequency range beyond 10 MHz ............................................................................................228.3.3 Recommended flowchart for selecting an evaluation method and measurement
method........................................................................................................................................23
Annex A (informative) Excerpt from the Radio Act related provisions................................... 27
Annex B (informative) Excerpt of related provisions of the Regulations for Enforcement of theRadio Act............................................................................................................................... 29
Annex C (informative) Notification of the Ministry of Posts and Telecommunications, No. 301
of 1999 ................................................................................................................................... 31
Annex D (informative) Notification of the Ministry of Posts and Telecommunications, No. 300
of 1999 ................................................................................................................................... 33
Annex E (informative) Safety measures against heat or other causes ..................................... 42
Annex F (informative) Explanation of radio-radiation protection guidelines ......................... 44
Annex G (informative) Examples of exposure calculation ...................................................... 56
Appendix 1. Wireless power transmission beyond 50 W ........................................................ 58
Reference Standards .............................................................................................................. 60

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GUIDELINES FOR THE USE OF WIRELESS POWER
TRANSMISSION/TRANSFER TECHNOLOGIES
1. Scope
These guidelines apply to wireless power transmission/transfer equipment meeting the following
performance conditions.
-

Transmission power does not exceed 50 W-

Power transmission/transfer distance does not exceed several meters-

Transmission frequencies: 10 kHz to 10 MHz, 13.56 MHz band (ISMband), 27.12 MHz band (ISM band), and 40.68 MHz (ISM band)

There is no restriction on the type of the equipment used or the power transmission/transfer method.
Since these guidelines were revised, wireless power transmission/transfer technologies that weredifferent from the performance of the above have been examined or researched/developed, and theirstandardization is now being considered. These guidelines will be reviewed and amended as required,in accordance with the progress of technical development, institutionalization, and standardization.

Remark 1: When applying these guidelines, note the following.
- In these guidelines, the usage scenes of wireless power transmission/transfer technology
are categorized as shown in Section 6 “Classification.” In edition 2.0, the guidelines
cover the wireless power transmission/transfer technology falling under the usage scene
1 and 2, along with usage scene 5 with a transmission power below 50 W.
- Various discussions are now being conducted concerning other usage scenes as well.
Although usage scene 3 and 4, along with usage scene 5 with a transmission power
beyond 50 W in Section 6 “Classification,” are not covered in the guidelines, Appendix
1 is added as a reference for institutionalization.
- The contents of “8.2 Safety measures for equipment or systems using wireless powertransmission/transfer technologies” and “8.3 Conformance to radio-radiation protection
guidelines” are applied to the more extensive usage scenes, in addition to usage scene 1
and 2, along with the usage scene 5 that falls under the category of transmission power
below 50 W.
- These guidelines are stipulated so that they conform to laws and regulations in Japan asof the time of this writing. At the same time, they assume that the use of wireless powertransmission/transfer technologies is widely extended at home and abroad.
- In countries other than Japan, additional requirements may be imposed by theirregulating authorities.
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Remark 2: These guidelines do not apply to the following devices, falling under the category of“Inductive reading and writing radio communication equipment” and “Mobile
object-identifying radio communication equipment ” in the current Radio Act.
- Contactless IC card readers/writers- Passive RFID interrogators

2. Applicable regulations and normative references
2.1 Applicable regulations
The following rules (laws) apply to the wireless power transmission/transfer covered by theseguidelines. If there is any difference in interpretation between these guidelines and the following
rules (laws), the interpretation of the following rules (laws) takes precedence over these guidelines.
[1] Radio Act (Law No. 131 of May 2, 1950) (See Annex A.)[2] Regulations for Enforcement of the Radio Act(Radio Regulatory Commission Rules No. 14 ofNovember 30, 1950) (See Annex B.)[3] The strength of the radio wave in frequencies between more than 10 kHz and 100 kHz or less andthe strength of the radio wave when the human body is exposed to the radio wave inhomogeneously,
pursuant to the rule of the Regulations for Enforcement of the Radio Act, Appended Table 2, 2-2,
Note 3 (Notification of the Ministry of Posts and Telecommunications, Number 301 of April 27,1999) (See Annex C.)[4] The methods of calculating and measuring the strength of the radio wave that is emitted from theradio equipment, pursuant to the rule of the Regulations for Enforcement of the Radio Act, Article 21,
Paragraph 3, Item 2 (Notification of the Ministry of Posts and Telecommunications, Number 300 of
April 27, 1999) (See Annex D.)

2.2 Normative references
The following standards contain provisions which, through reference in these guidelines, constitutepart of the provisions of these guidelines. If the indication of the year of coming into effect or theyear of publication is given to these referred standards, only the edition of the indicated year
constitutes the provision of these guidelines, and the revision and amendment made thereafter do not
apply. The normative references without the indication of the year of coming into effect or the yearof publication apply only to the most recent edition (including amendments).
[5] Radio-radiation Protection Guidelines (Report of the Telecommunications Technology Council ofthe Ministry of Posts and Telecommunications [June 1990]: Inquiry No. 38 “Human Body Protection
Guidelines for the Use of Radio Waves”)[6] Radio-radiation Protection Guidelines (Report of the Telecommunications Technology Council ofthe Ministry of Posts and Telecommunications [April 1997]: Inquiry No. 89 “Method of Protecting
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Human Bodies for the Use of Radio Waves”)[7] ICNIRP Guidelines for limiting exposure to time-varying electric, magnetic, and electromagnetic
fields (up to 300 GHz)
[8] IEEE std C95.1-2005: IEEE Standard for Safety Levels with Respect to Human Exposure toRadio Frequency Electromagnetic Fields, 3 kHz to 300 GHz.
[9] IEC 62311: Assessment of electronic and electrical equipment related to human exposure
restrictions for electromagnetic fields (0 Hz - 300 GHz).
[10] IEC 62233: Measurement methods for electromagnetic fields of household appliances andsimilar apparatus with regard to human exposure.
[11] IEC 60990 Ed. 2.0:1999 (b) Methods of measurement of touch current and protective conductor
current[12] IEC 60335-1 Household and similar electrical appliances - Safety - Part 1: General
requirements[13] IEC 60950-1:

Information technology equipment - Safety - Part 1: General requirements

3. Definitions
The definitions of the main terms used in these guidelines are shown below.
3.1. Wireless power transmission/transfer: Transmitting/Transferring and receiving electricenergy among two or more pieces of equipment that are not connected through conductors byelectromagnetic means
3.2. Transmitted/Transferred power: Powertransmitted/transferredfrom thepowertransmission/transfer side in a wireless power transmission/transfer
3.3. Power transmission/transfer distance: In wireless power transmission/transfer, the distance
between the center of a coil or another component that generates an electromagnetic field andthe center of the component that receives the electromagnetic field; if the component is covered
with resin or other material, it may mean the distance between their surfaces.
3.4. Type of power transmission/transfer: The way of generating an electromagnetic field for
power transmission/transfer and the method of combining the transmission and reception sides
in wireless power transmission/transfer; the types include electromagnetic induction type,magnetic resonance type, electric resonance type, and radio emission type.
3.5. Transmission frequency: In wireless power transmission/transfer, the frequency of theelectromagnetic field that transmits/transfers electric energy; there are cases where informationtransmission is performed between transmission and reception sides with a frequency that isdifferent.
3.6. Industrial, Scientific, and Medical band: Frequency bands for industrial, scientific, andmedical purposes stipulated in the Radio Regulations of the Constitution of International
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Telecommunication Union; note that some of the frequency bands that are not applicable inJapan.
3.7. High frequency-based equipment: Specific equipment using a high-frequency current of 10
kHz or more, which is stipulated in Radio Act, Article 100, Paragraph 1
3.8. Inductive radio communication equipment: Equipment that performs communication byusing induced radio waves generated by flowing a high-frequency current of 10 kHz or more
into a power line
3.9. Transmission side: In wireless power transmission/transfer, the side of transmitting/transferring power
3.10. Reception side: In wireless power transmission/transfer, the side of receiving power
3.11. Temperature rise limit: Allowable limit value specified in these guidelines concerning thetemperature rise that occurs on the surface and periphery of the equipment and on the surface ofalien substances inserted into the equipment during the operation of the equipment; thereference value of the temperature rise is set to 25°C.
3.12. Alien substance: A substance that is not necessary for power transmission/transfer but isaccidentally inserted between the transmission and reception sides
3.13. Test piece: A metal piece with a shape defined for a test, particularly assumed as a metallic
alien substance3.14. Coil: A coil for transmitting/transferring or receiving power in the transmission or reception
side in wireless power transmission/transfer; in these guidelines, an electrode having a shapeother than a coil, a transmission antenna, and a receiving antenna used for the same purpose arealso treated as equivalent to a coil. If a coil is built into the equipment, the coil may not be able
to be recognized from the outside. Therefore, when applying these guidelines, it may benecessary to check the position of the coil by using certain measures.
3.15. Coil plane: Of the planes perpendicular to the coil axis, the part that includes the center
point of the coil shape and to which the circumference of the coil is projected vertically is thecoil plane. If the coil is not exposed on the equipment, the entire plane perpendicular to the coilaxis, out of the surface of the equipment containing the coil, is treated as the coil plane.
3.16. Radio-radiation protection guidelines: Recommended guidelines used when a person uses
radio waves and whose body is exposed to an electromagnetic field (in a frequency range of 10
kHz through 300 GHz) to ensure that the electromagnetic field is safe without producing an
unnecessary biological effect on the human body; these guidelines consist of numeric values
related to electromagnetic strength, the method of evaluating the electromagnetic field, and theprotection method to reduce electromagnetic field irradiation. [5]3.17. Basic guidelines: Guidelines for evaluating the safety of the human body based on various
biological effects (body-core temperature elevation, current stimulation, high-frequency burns,
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etc.), which may occur to the human body when it is exposed to an electromagnetic field; it ispositioned as the basis of the concept of the Radio-radiation Protection Guidelines anddescribed in SAR, induced current, and contact current. [5]3.18. Administrative guidelines: Guidelines used for actual evaluation indicated by the actual
measurable physical amount in order to meet the basic guidelines (electric field strength,
magnetic field strength, power density, current, and specific absorption rate), and the guidelines
consist of electromagnetic field strength guidelines, supplementary guidelines, and partial bodyabsorption guidelines. [5]3.19. Electromagnetic field strength guidelines: Guidelines for evaluating the safety of thetarget space from the standpoints of the electric field strength, magnetic field strength, andpower density; if the radiation source is located at a sufficiently distant location and if there isno metal or other object that scatters radio waves at a place close to the space in which thehuman body exists, it can be assumed that the electromagnetic phenomenon inside the humanbody in the space bears an almost constant relation to the electric field strength and themagnetic field strength measured when the human body does not exist in said space. Under
such a condition, protection guidelines can be set by using the electromagnetic field strength ina space in which no human body exists. This guideline is called the electromagnetic fieldstrength guideline. Because the electromagnetic field covered by the protection guideline isusually a near field or an inhomogeneous place, the electromagnetic field strength guidelinecannot apply as it is in many states. In an electromagnetic environment that does not meet suchconditions, there are cases where evaluation only of the space is not appropriate. In this case, itis necessary to return to the basic guidelines when performing an evaluation. [5]3.20. Supplementary guidelines: Guidelines used to perform a detailed evaluation based on thebasic guidelines when the electromagnetic field strength guidelines are not met; if the state
exposed to the electromagnetic field (e.g., inhomogeneous, partial, or surface exposure), target
biological effects (contact current and induced current), and the attribute of the radio
wave-emitting source (antenna power and frequency band) are obvious, guidelines are shown
based on these statues in a form such that the application of the electromagnetic field strength
guidelines is relaxed or excluded. In addition, because the basic guidelines contain descriptions
using immeasurable amounts, they cannot be used as practical protection guidelines if an
attempt is made to evaluate all the inter-relationships between the electromagnetic radiation
source and the human body based on the basic guidelines. To practically cope with this problem,
it is necessary to establish guidelines with measurable evaluation amounts. These guidelines arecalled the supplementary guidelines. The supplementary guidelines are provided in the form of
supplementing the electromagnetic field strength guidelines based on the basic guidelines, andthey include:
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BWF TR-01(1) Guidelines for when the human body is exposed to an electromagnetic field
inhomogeneously or partially;(2) Guidelines concerning the contact current; and(3) Guidelines concerning induced ankle current.
The supplementary guidelines have the character of a simplified evaluation method for theelectromagnetic phenomenon inside the human body, as an alternative to the basic guidelines.
Therefore, it is necessary to bear in mind that they should originally be handled as basic
guidelines. [6]3.21. Partial body absorption guidelines: These guidelines are used to perform detailed
evaluation based on the basic guidelines when a part of the human body is intensively exposed
to an electromagnetic field due to electromagnetic waves mainly emitted from radio equipmentthat is used at a place quite near to the human body. [6]3.22. Controlled environment: An environment in which a state where the human body is
exposed to an electromagnetic field is recognized, the radiation source of the radio wave can be
identified, and control appropriate to the state can be performed. [6]3.23. General environment: A case (environment) in which a state where the human body is
exposed to an electromagnetic field cannot be recognized, appropriate control cannot be
expected, and uncertain factors exist; for example, the state where residents are exposed to theelectromagnetic field in general residential environment falls under this case. Therefore, theguidelines applied to the general environment are stricter than those applied to the controlledenvironment. [5]3.24. Homogeneous exposure: Exposure of the whole human body to an electromagnetic field ofa space in which the human body exists in states where the electromagnetic field of the spacecan be regarded as almost homogeneous; in this case, the condition where the free space
impedance is less than 120  [Ω] is also included in this category. In a free space, theelectromagnetic field is considered to be homogeneous if the distance from the wave source issufficiently great compared with the body height. (For example, 15 m or more in a frequency of
0.3 MHz or less, 10 m or more in a frequency of 0.3 MHz to 300 MHz, and 5 m or more in afrequency of 300 MHz or more). [5]3.25. Inhomogeneous exposure: A case where the exposure is not regarded as homogeneous
exposure [5]3.26. Partial body exposure: A case where a part of the human body is intensively exposed to anelectromagnetic field; it includes irradiation at a place quite near to an antenna that is muchsmaller than the human body and spot irradiation due to radio waves with a short wavelength.
[5]3.27. Whole body exposure: A case where the whole body, rather than only part of a body, is
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exposed to an electromagnetic field; the case where exposure is not partial though exposure is
not necessarily homogeneous falls under this category. [5]3.28. Averaging duration: Time for measurement set based on the noted biological effect in orderto evaluate the conformity to the guideline value; the average time used in Radio-radiation
Protection Guidelines is one second or less in stimulant action and six minutes in thermal action.
[5]
3.29. Specific Absorption Rate (SAR): Energy amount that is absorbed in unit time by the tissue
of unit mass when a biological body is exposed to an electromagnetic field; the SAR that isaveraged throughout the body is called the “whole-body average SAR,” and the SAR that isaveraged for 1 g or 10 g of any tissue of the human body is called the “local average SAR.” [6]3.30. Contact current: A current that flows through the contact point when the grounded humanbody touches the non-grounded conductive substance placed in the electromagnetic field [5]3.31. Contact hazard: A potential state that generates a contact current [5]3.32. Induced current (density): A current (density) that is induced into the human body when
the human body is exposed to an electromagnetic field [5]3.33. Ungrounded condition: A condition in which the influence of the ground can be ignored
because the induced current does not flow into the ground; for bare feet, for example, thiscondition applies when the feet are 10 cm or more apart from the ground [5]3.34. Far field: An electromagnetic field in conditions where the distance from theelectromagnetic wave source is farther than both 2 D2/ and /2 and where there is noreflection and scattering; where, D denotes the maximum size of the antenna and  denotes the
wavelength of the free space. [5]3.35. Near field: An electromagnetic field that is not a far field [5]3.36. Electromagnetic field prove (sensor): An antenna system with isotropy and broadband
characteristics given by placing a physically small dipole antenna or loop antenna orthogonallyto the two or three axes, as well as with improved interference characteristics by using ahigh-resistance line; it is mainly used for isotropic broadband electromagnetic field strength
meters. [5]3.37. Isotropy: A characteristic of a probe (or antenna) in which sensitivity is not dependent on
the incident direction of electromagnetic waves [5]4. General requirement
The equipment to which these guidelines apply should conform to the laws and rules of the country
in which the equipment is used and should have a structure that functions in a safe manner so that it
does not do harm to the human body and the environment—even during the carelessness that often
occurs in normal use.
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This principle is accomplished by meeting the requirements related to these guidelines, and whether
the requirements are met is checked by conducting all the related tests.

5. General requirement for the tests
Tests should be conducted in accordance with the laws and rules of the country in which theequipment is used, if any. If there are no such laws or rules, tests should be conducted in accordancewith the international standards such as IEC or another appropriate domestic standards (JIS in Japan),unless otherwise specified in the guidelines.

6. Classification
In these guidelines, equipment using wireless power transmission/transfer technology isclassified into several types of usage scenes as shown in Table 6-1. These guidelines apply
to the equipment falling under the usage scene 1 and 2, along with usage scene 5 with atransmission power below 50 W.
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Table 6-1: Wireless power transmission/transfer technology usage scenes
Usage

Assumed usage

scene

scene
Close
proximity
wireless
power
transmissionofhousehold digitalappliances, etc., forhome and outdoor
use

Usage
scene 1

Low-power
wireless
power
transmissionofhousehold digitalappliances, etc., forhome and outdoor
use
Usage
scene 2

Usage
scene 3Medium-power
wirelesstransmissionofhouseholdelectricalappliances, etc., forhome and outdoor
useConcrete application examples

Specifications and functions of the usage
scene

Wireless power supplies and wirelesscharging for the following:(1) Cellular phones, smartphones(2) Notebook PCs, tablet PCs(3) Wall TVs, portable TVs(4) Digital still cameras, video
cameras(5) Portable music players(6) Audio equipment (speakers,
headphones, etc.)(7) Lighting equipment(8) Industrial equipment(9) Medical equipment, health careequipment(10) Game instruments, toys(11) On-board equipment(12) Business equipment
Wireless power supplies and wirelesscharging for the following:(1) Cellular phones, smartphones(2) Notebook PC, tablet PCs(3) Wall TVs, portable TVs(4) Digital still cameras, video
cameras(5) Portable music players(6) Audio equipment (speakers,
headphones, etc.)(7) Lighting equipment(8) Industrial equipment(9) Medical equipment, health careequipment(10) Game instruments, toys(11) On-board equipment(12) Business equipment
Wireless power supplies and wirelesscharging for the following:(1)
Floor-standing
householdelectrical appliances (refrigerators,
washing machines, air conditioners)(2) Household electrical heating
appliances (dryers, irons, ricecookers, hot plates, etc.)(3) Vacuum cleaners, etc.
(4)AVhouseholdelectricalappliances (large TVs, etc.)(5) Hairdressing equipment(6) High-output lighting equipment(7) Electric carts, two-wheeled
electric vehicles

13(1) Frequency: 10 kHz to 10 MHz, ISM
band, (13 MHz, 27 MHz, 40 MHz)
(2) Transmission power: Up to 50 W
(3) Power transmission distance: Up toabout 10 cm(1) Frequency: 10 kHz to 10 MHz, ISM
band, (13 MHz, 27 MHz, 40 MHz)
(2) Transmission power: Up to 50 W
(3) Power transmission distance: Up toseveral meters(1) Frequency: 10 kHz to 10 MHz, ISM
band, (13 MHz, 27 MHz, 40 MHz)
(2) Transmission power: 50 to several
kW(3) Power transmission distance: Up toseveral 10s of centimeters

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High-power
wireless
power
transmission
Usage
scene 4

(1) Wireless power supplies andwireless charging for electric vehicles（including plug-in hybrid cars）(2) Wireless power supplies andwirelesscharging
for
trams(streetcars), etc.
(3) Industrial applied equipment (forfactories, etc.)
Variouswireless
power transmissionthat operates using
microwaves(1) Frequency: 20 kHz to 150 MHz(2) Transmission power: 1 kW to several
10s of kW(3) Power transmission distance: Up toabout 30 cm(1) Frequency: Several kilohertz toseveral hundreds of kilohertz(2) Transmission power: Several
kilowatts to several 10s of kilowatts(3) Power transmission distance: Up toabout 30 cm(1) Wireless power supplies for(1) Frequency: ISM band （ 2.4-GHz

wireless sensors (for environmental

band, 5.8-GHz band, 24-GHz band）

monitoring, etc.)(2) Transmission power: Up to 1 kW

(2) Lighting equipment(3) Power transmission distance: Up to(3) Wireless power supplies to areas

about 1 km

where power line installation isdifficult(4) Wireless power supplies for(1) Frequency: ISM band（2.4-GHz

portable equipment (smartphones,

band, 5.8-GHz band）

Tablet PCs, etc.)(2) Transmission power: Up to 50 W
(3) Power transmission distance: Less
than about 1 cm (almost contacting)Usagescene 5

(5) Shared use of wireless power(1) Frequency: ISM band (5.8-GHztransmission and high-speed wirelessband, 24-GHz band), 60-GHz band,communication using wirelessunused frequency band among the range

communication repeatersof 31.5 GHz to 54.25 GHz(2) Transmission power: Up to 50 W
(3) Power transmission distance: Up toabout 5 m

(6) Wireless power supplies and(1) Frequency: ISM band（5.8-GHz

wireless charging for electric vehicles

band, 24-GHz band）,unused frequency（including plug-in hybrid cars）

band among the range of 31.5 GHz to54.25 GHz
(2) Transmission power: 500 W–6 kW(3) Power transmission distance:
About 2 m to 9 m

7. Marking and instructions
Manufacturers or distributors who apply these guidelines can describe the conformity to these14

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guidelines on their appliances or user manuals after confirming that these appliances conform tothese guidelines.

8. Conditions for the use
8.1 Radio Acts referenced by these guidelines
In the present act, the high frequency-based equipment that requires permission to install theequipment is stipulated in the Radio Act, Article 100, Paragraph 1. (See Annex A.) These guidelines
apply to the equipment that is exempt from the regulations of the Radio Act, conforming to therequirements of the high frequency-based equipment that do not require permission.

8.1.1 Requirements of high frequency-based equipment covered by these guidelinesthat do not require permission
In the regulations of the present Radio Act-related rules, the requirements of Paragraph 8.1
exemptions are met in any of the following cases.
- High frequency-based equipment other than communications equipment, in which thehigh–frequency energy is 50 W or less (interpretation from Regulations for Enforcementof the Radio Act, Article 45, Paragraph 3) (See Annex B.)- Inductive radio communication equipment (which refers to equipment that performs
communication by using an inductive radio wave that is generated by flowing ahigh-frequency current of 10 kHz or more into a power line), in which the electric fieldstrength at a distance of /2 (where,  is the wavelength of the carrier wave in metersand  is the circular constant) is 15 V/m or less (Regulations for Enforcement of theRadio Act, Article 44, Paragraph 1, Item 2-(1)) (See Annex B.)
Even if the above requirements are met, if the equipment causes continuous and serious
trouble to the functions of other radio equipment, the Minister for Internal Affairs andCommunications can order the taking of necessary action to remove the trouble (Radio Act,
Article 82, Paragraph 1, which is applied mutatis mutandis pursuant to the Radio Act,
Article 101). (See Annex A.) Therefore, it is necessary to give consideration so that theequipment does not cause trouble for other radio equipment.

8.2 Safety measures for equipment or systems using wireless power transmission/transfer
technologies
The wireless power transmission/transfer equipment or systems covered by these guidelines must
deploy safety measures as follows.

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8.2.1 Basic safety measurements
The equipment or systems using wireless power transmission/transfer technologies are essentiallyappliances for transmitting/transferring or receiving power. The wireless power transmission/transfer
equipment therefore must have the same safety features as electrical products.
Most electrical products are required to implement safety features conforming to the IEC 60335“Household and similar electrical appliances – Safety –” to ensure a minimum level of safety forusers. In a similar way, wireless power transmission/transfer equipment or systems must basicallymeet and implement the safety requirements specified in IEC 60335 or IEC 60950 “Information
Technology Equipment – Safety –.”For the product and safety standard of electrical vehicles, which are not covered in the present
guidelines, a standardization discussion is now being conducted, based on the “4. Standardization
trend” in Appendix 1 “Wireless power transmission/transfer at higher than 50 watts.” When theguidelines are revised to have electrical vehicles covered by them, referring to the appendix above
will be considered.

8.2.2 Safety measures specific to wireless power transmission/transfer
Equipment or systems using wireless power transmission/transfer technologies, which employ
technologies different from those used for typical electrical products, are required to implement
safety or hazard-avoidance measures specific to them.
The safety measures required for wireless power transmission/transfer equipment or systems are as
follows.

8.2.2.1 Identification of reception sides and power transmission restrictions
Power transmission/transfer equipment (transmission equipment) shall be equipped with the ability
to identify reception sides (reception equipment) and transmit power safely. When reception
equipment cannot be identified, transmission equipment shall not transmit power. Any identification
method can be employed.
When equipment fails to transmit power appropriately, it is not allowed to transmit power eventhough reception sides can be identified.

8.2.2.2 Measures to prevent metal pieces located in the path of the power transmission linefrom overheating
In a wireless power transmission/transfer technology where a metal piece that is located on the pathof the power transmission line is subject to overheating, the upper limit of the temperature that themetal piece is allowed to reach shall conform to the IEC 60335. Also, take safety measures against
possible overheating. Such safety measures include a metal detection ability to prevent the risk of16

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overheating, or an ability to stop power transmission when the overheating of a metal piece could
occur.
For the method of measuring the temperature rise of a metal piece located in the path of the powerline to prevent overheating, see Annex E.

8.2.2.3 Measures to prevent metal pieces located at the periphery of the power transmission
equipment (transmission equipment) or reception equipment from overheatingWith the method with which an electromagnetic field is generated at the periphery of the powertransmission equipment (transmission equipment) or reception equipment, take safety measures sothat any metal piece located in that area will not be overheated.

8.2.2.4 Safety measures to protect any human body that is located in the path, or at the
periphery, of the power transmission line
In the case where wireless power transmission/transfer equipment or systems are under normal use
and when all or part of a human body is located in the path, or at the periphery, of the powertransmission line, safety measures shall be taken so that the human body protection guidelines in theRadio Act or the international guidelines (described in section 8.3 in the present guidelines) aresatisfied. Any wireless power transmission/transfer equipment or system mentioned above to which
all or part of a human body may come close shall be equipped with the ability to notify users that theprotection guidelines are exceeded, stop the power transmission after detecting an abnormal
condition, or decrease the power transmission output.

8.2.2.5 Safety measures for the case where a non-metal piece is located in the path of the powertransmission line
In the case where a non-metal piece located in the path of the power transmission line causes
abnormal power transmission, resulting in an irregular leakage electromagnetic field, the wirelesspower transmission/transfer equipment or system shall be equipped with the ability to stop the powertransmission or decrease the power transmission output after detecting an abnormal condition.

8.2.2.6 Safety measures for the location of reception equipment
In the case where the transmission and reception equipment is limited in location during powertransmission, the wireless power transmission/transfer equipment or system shall be equipped withthe ability to stop the power transmission when its location is out of the scope of the design
specifications, which could lead to an irregular leakage electromagnetic field stronger than the one
produced in normal use.

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BWF TR-01

8.2.2.7 Safety measures against abnormal operation during power transmission
In the case where an abnormal operation out of the scope of the design specifications, such asincreased power load beyond specifications, is caused due to an abnormal condition or a failure of
the transmission or reception equipment during power transmission, the wireless powertransmission/transfer equipment or system shall be equipped with the ability to stop the powertransmission or decrease the power transmission output.

8.2.3 Safety measures for other types of wireless power transmission/transfer equipment or
systems
The wireless power transmission/transfer methods other than that said above that require a specificsafety measure are as follows.

8.2.3.1 Safety measures for a wireless power transmission/transfer technology that operates on
microwave technology
The following safety measures shall be implemented besides the ones specified from section 8.2.2.1
to section 8.2.2.7.
In the case where a human body is located between the transmitting antenna and the receiving
antenna, affecting power transmission, safety or risk-avoidance measures shall be taken for thedetection of the human body, intrusion prevention, or the structure that prevents the human bodyfrom intruding.
Also some countermeasures have to be taken to prevent a side lobe leakage, which is caused on thepath between the transmitting antenna and the receiving antenna, from becoming higher than thelevel specified in the design specifications.

8.2.3.2 Safety measures for a wireless power transmission/transfer technology that operates oncoupled electromagnetic field
In a wireless power transmission/transfer technology that operates on a coupled electromagnetic
field, the human body could make contact with a component of the equipment, causing an electricalshock. The equipment therefore is required to implement safety measures to prevent human bodycontact and to stop the power transmission when such contact is detected.

8.3 Considerations for the radio-radiation protection guidelines
8.3.1 Principles
For the equipment to which these guidelines apply, it is necessary to verify that the electromagnetic
field generated by the equipment does not do harm to the biological body during normal use status
and to the environment by using a scientific evaluation method such as by measurement.
18

BWF TR-01

In Japan, the equipment should in principle follow the Radio-radiation Protection Guidelines
reported by the Telecommunications Technology Council of the former Ministry of Posts andTelecommunications (the present Ministry of Internal Affairs and Communications).
Internationally, on the other hand, the ICNIRP (International Commission on Non-Ionizing
Radiation Protection) guidelines and ICES (International Committee on Electromagnetic Safety) of
the IEEE (Institute of Electrical and Electronics Engineers) standards are referred to as theauthoritative guidelines, the latest editions of which are followed in the present guidelines as
required.
Note: The radio-radiation protection guidelines set by the Japanese government, ICNIRP, and IEEEare hereinafter referred to as the “domestic guidelines,” “ICNIRP guidelines,” and “IEEE
guidelines,” respectively. Also, the excerpts of those guidelines are attached as Annex F forreference.
8.3.2 Evaluation category for electromagnetic field exposure by frequency range

The effects of electromagnetic field exposure vary with frequency range. Therefore, for eachfrequency range, the guideline values, evaluation method, and measurement method to be appliedshould be defined. Also, a wide variety of implementations in wireless power transmission/transfer
equipment and many different cases regarding the distance between the equipment and the humanbody make it difficult to narrow down evaluation or measurement methods into a single specific one.
The present guidelines thus provide a procedure for selecting an appropriate one from the several
methods available for each frequency range. Users of the guidelines should select an evaluation ormeasurement method that they think is appropriate and should evaluate the effect under a condition
expected in normal use. The evaluation method, the measurement method, and the evaluation
conditions employed should be pointed out explicitly in the resulting data.

Note: The frequency range classification shown below is in accordance with the domestic guidelines
and the ICNIRP guidelines. The IEEE guidelines use a frequency range classification different fromthe one shown here. For details, see Annex F.

Table 8.3.2: Evaluation category for electromagnetic field exposure classified by frequency range

Usage scenes

Usage scene 1 and 2

Usage scene 4 (1)Usage scene 3

Electric vehicles
Frequency range
Transmission power

A

B

C

Up to 50 W

19

A

B

C

A

B

50 W to several

1 kW to several 10s ofkilowatts

kW

BWF TR-01

Transmission distance

Up to several meters

Up to about several 10s

Up to about 30 cm

Evaluation categories

of centimeters(1)

Stimulant effectThermal effectContact current

(1)

(2)

(3)

(2)

(4)

Induced current

(5)

(3)

(6)
(8)

(4)
(9)

(7)

(9)

(9)

A, B, and C represent the following ranges of frequency, respectively.
Frequency range A

10 kHz–100 kHz

Frequency range B

100 kHz–10 MHz

Frequency range C

13.56 MHz, 27.12 MHz, 40.67 MHz

Most peripheral electromagnetic fields generated by wireless power transmission equipment provide
the case where the electromagnetic field is inhomogeneous or where the human body is exposed tothe electromagnetic field only partially. While keeping this fact in mind, the evaluation items forelectromagnetic field exposure by frequency range are described as follows.

8.3.2.1 [Frequency range A] Evaluation categories for the electromagnetic field exposure in thefrequency range of 10 kHz to 100 kHz(1)Categories related to stimulant effect ((1) and (5))
In the domestic guidelines, reference values are provided in the electromagnetic field strength
as a measurable administrative guideline.
Table F-1 in Annex F shows the spatial averages of the electric field and magnetic field interms of stimulant effect, with the average time of less than one second.
In the case where the electromagnetic field is inhomogeneous or the human body is partially
exposed to an electromagnetic field, in the space more than 20 cm away from theelectromagnetic radiation source and metal substance, the spatial average of the power
density distribution in the entire area corresponding to the space that the human bodyoccupies (for the electric field strength and magnetic field strength, their root mean squarevalue) shall be less than the guideline value of the electromagnetic field strength.
Note that for the equipment used in the space within 20 cm of the human body, a decision on a
20

BWF TR-01

case-by-case basis is required. If it is anticipated that the basic guideline values can beexceeded, an evaluation based on the basic guidelines is recommended.

In the ICNIRP guidelines for the low-frequency range, which was revised in 2010, only thevalues associated with stimulant effect are defined for this frequency range. Table F-3 shows
the measurable reference levels.
For an extremely localized radiation source located within a few centimeters of the human
body, determine the induced electrical field through an individual evaluation of the exposure.
When the radiation source is more than 20 cm away from the human body, the spatial averageof the electric field and magnetic field can be obtained, even though the electromagnetic field
is inhomogeneous. The amount of localized exposure is allowed to exceed the reference levelbut not the basic guideline values.

(2)

Categories related to thermal action ((2) and (6))
In the domestic guidelines, the guideline values for thermal effect are also defined, which isshown in Table F-2.
This means that, in the domestic guidelines, both stimulant effect and thermal effect have tobe taken into account in this frequency range.
In the ICNIRP guidelines, no guideline values for thermal action are defined for thisfrequency range.

(3)

Categories related to contact current ((4) and (8))
Both in the domestic guidelines and the ICNIRP guidelines, contact current is required to beevaluated in this frequency range.
In the domestic guidelines, the guideline values for contact current are provided in thefrequency range of 10 kHz to 15 MHz. Also, when the emission source is within 20 cm of thehuman body, contact current is defined in the frequency range of 100 kHz to 100 MHz as thepartial body absorption guidelines, when a contact hazard cannot be prevented.
In the ICNIRP guidelines, reference values for the contact current are defined in the frequency
range of 2.5 kHz to 10 MHz.
In the IEEE guidelines, they are defined in the frequency range of 3 kHz to 110 MHz.

8.3.2.2 [Frequency range B] Evaluation items for electromagnetic field exposure in thefrequency range of 100 kHz to 10 MHz(1)

Categories related to stimulant effect ((1) and (5))
21

BWF TR-01

In the ICNIRP guidelines for the low-frequency range, which were revised 2010, the reference
values for the stimulant effect is defined also for this frequency range. In the domestic
guidelines, no reference values for the stimulant action are defined for this frequency range(See Table F-3).
This means that, in the ICNIRP guidelines for the low-frequency range, which were revised in
2010, both stimulant effect and thermal effect have to be taken into account in this frequency
range.

(2)

Categories related to thermal action ((3) and (7))

In the domestic and ICNIRP guidelines, the reference values for thermal effect are defined,
which are shown in Table F-2 and Table F-3, respectively.
For the evaluation method and measurement method for this frequency range, IEC 62311
should be referred to.

(3)

Items related to contact current ((4) and (8))

Both in the domestic guidelines and the ICNIRP guidelines, contact current is required to beevaluated in this frequency range.
In the domestic guidelines, the guideline values for contact current are provided in thefrequency range of 10 kHz to 15 MHz. Also, when the radiation source is within 20 cm of thehuman body, contact current is defined in the frequency range of 100 kHz to 100 MHz as thepartial body absorption guidelines, when contact hazard cannot be prevented.
In the ICNIRP guidelines, guideline values for the contact current are defined in the frequency
range of 2.5 kHz to 10 MHz. In the IEEE guidelines, they are defined in the frequency range of3 kHz to 110 MHz.

(4)

Items related to induced current (9)Both in the domestic guidelines and the ICNIRP guidelines, induced current is required to beevaluated in this frequency range.
In the domestic guidelines, the guideline values for induced ankle current are provided in thefrequency range of 3 MHz to 300 MHz.
In the ICNIRP guidelines in ICNIRP1998, the guideline values for the induced current in
extremities are defined in the frequency range of 10 MHz to 110 MHz.

8.3.2.3 [Frequency range C] Evaluation items for the electromagnetic field exposure in the22

BWF TR-01

frequency range above 10 MHz(1)

Items related to thermal effect (3)In the domestic and ICNIRP guidelines, the guideline values for thermal effect are defined,
which are shown in Table F-2 and Table F-3, respectively.
In ICNIRP1998, the reference levels (of electrical field strength, magnetic field strength,
magnetic flux density, equivalent plane wave power density) are defined based on the basic
limits of the whole-body average SAR in the frequency range equal to or higher than 10 MHz.
The spatial average value of the entire body exposed to the electromagnetic field is evaluated.
In a localized exposure, the measured SAR values shall not exceed the local average SAR.

(2)

Items related to contact current (4)Both in the domestic guidelines and the ICNIRP guidelines, contact current is required to beevaluated in this frequency range.
In the domestic guidelines, the guideline values for contact current are provided in thefrequency range of 10 kHz to 15 MHz. Also, when the emission source is within 20 cm of thehuman body, the guideline values for contact current are defined in the frequency range of 100
kHz to 100 MHz as the partial body absorption guidelines, when contact hazard cannot be
prevented.
In the ICNIRP guidelines, guideline values concerning the contact current are defined in thefrequency range of 2.5 kHz to 10 MHz. In the IEEE guidelines, they are defined in thefrequency range of 3 kHz to 110 MHz.

(3)

Items related to induced current (9)Both in the domestic guidelines and the ICNIRP guidelines, induced current is required to beevaluated in this frequency range.
In the domestic guidelines, the guideline values for induced ankle current are provided in thefrequency range of 3 MHz to 300 MHz.
In the ICNIRP guidelines in ICNIRP1998, the guideline values for the induced current in
extremities are defined in the frequency range of 10 MHz to 110 MHz.

8.3.3 Recommended flowchart for selecting an evaluation method and measurement method
The procedure for the evaluation of the electromagnetic field exposure is as follows.
(1)

Determine the guidelines to be applied. (Domestic guidelines, ICNIRP guidelines, etc.)

23

BWF TR-01(2)

When the domestic guidelines are applied, evaluate the exposure based on the notification of
the Ministry of Posts and Telecommunications, No. 300 of 1999, shown in Annex D.

In the case where the human body could be within 20 cm of the equipment, follow the next procedure.
A decision on a case-by-case basis is required.

(2-a) First, evaluate the maximum electromagnetic field strength in the space that the human bodyoccupies when it approaches nearest to the equipment. If the value does not exceed theelectromagnetic field strength guideline, it is determined to be compliance.
(2-b) If the electromagnetic field strength guideline is exceeded in any points in the area, employ theIEC 62311 evaluation method.

(3)

When the ICNIRP guideline is applied and the product or the family of products is covered by
the standard measurement methods from IEC, employ that method. If they are not covered by
the standard measurement methods from IEC, employ the IEC 62311, a horizontal standard.

The flowchart of the above procedure is shown in Figure 8.3.3-1.

Guidelines to be
appliedDomestic
guidelines？

No

Employ ICNIRP
guidelines or IEEE
standard

YesNo
Can be within 20cm of
the equipment ?

Yes

Evaluate the radio
wave strength based on
the notification of the
Ministry of Posts andTelecommunications,No. 300 of 1999

Employ the IEC
standard
Measurement method

No
IS there a standard for a productor family of products ?

A decision on a case-bycase basis is required.
If the basic guideline
values can be exceeded, anevaluation based on thebasic guideline values isrecommended (*)

Yes
Measure/evaluate basedon the standard for the
product or family of
products

Measure/evaluate basedon the IEC 62311, ahorizontal standard.

* Since specific guideline

IEC 62233

values are not provided,

IEC 62209-2

refer to the IEC 623111,(IEC PT61980), etc.

etc.

Fig 8.3.3-1. Flowchart for selecting an evaluation method and measurement method (1)24

BWF TR-01

Note:(1) IEC 62233：Measurement methods for the electromagnetic fields of household appliancesand similar apparatus with regard to human exposure(2) IEC 62209-2 ： Human Exposure to Radio Frequency Fields from Handheld andBody-Mounted Wireless Communication Devices – Human Models, Instrumentation, andProcedures – Part 2: Procedure to determine the specific absorption rate (SAR) for wirelesscommunication devices used in close proximity to the human body (frequency range of 30
MHz to 6 GHz).
(3) IEC PT61980：Electric vehicle wireless power transfer systems (draft）

25

BWF TR-01

IEC 62233

IEC 62311(Reference levelevaluation)
Measure a magnetic
field strength ormagnetic flux densityfrom the specified
distance（Reference levelevaluation）
Measure aelectromagnetic fieldstrength at the
specified location
Use coupling
coefficientBelowlimits?

No

Yes
Yes

Yes

Below
limits?
No

No

Determine theindividual coupling
coefficient

Yes

Below
limits?

Evaluate inconsideration of thebasic restrictions
Detail measurement or
exposure calculation

Below
limits?
No
Evaluate theexposurecalculation

Yes

Yes

Below
limits?

Belowlimits?
No

No
Compliance

Noncompliance

Compliance

Noncompliance

Fig 8.3.3-2. Flowchart for selecting an evaluation method and a measurement method (2)As an example of the IEC standard for a product family, the flowchart for IEC 62233, which defines
an exposure evaluation method for household electrical appliances, and IEC 62311, which is a
product horizontal standard, are shown in Figure 8.3.3-2. For details, see the respective references.

For the case in which the evaluation of the electromagnetic field exposure considering the basic
restrictions is required, various procedures are proposed, and the results of the latest researchdevelopments are expected to be reflected in them in the future. Although the present guidelines do
not recommend a specific method, examples of the exposure calculation method are shown in Annex
G for your reference.

26

BWF TR-01

Annex A (informative) Excerpt from the Radio Act related provisions(High frequency-based equipment)
Article 100(1) Any person who wishes to install the following facilities shall obtain permission from the
Minister of Internal Affairs and Communications:(i) Telegraphy, telephony or other telecommunications facilities which apply radio frequency
currents 10 kHz or above to the wired system (except power carrying cable facilities,
two-bare-wire balanced type power carrying facilities or other communications facilities which
are specified in the applicable MIC ordinance).
(ii) Radio facilities and facilities other than those of the preceding items, which use radio
frequency currents 10 kHz or above and are specified in the applicable MIC ordinance.
(2) Upon receipt of an application for permission under the preceding paragraph, the Minister ofInternal Affairs and Communications shall permit the construction in the application where
determining that the application satisfies the technical regulations of Article 28, 30 or 38 whichshall apply to paragraph (5) and the use of frequencies related to the application causes nointerference with other communications (including monitoring service at places specified in public
notices made by the Minister of Internal Affairs and Communications).
(3) When a person who has obtained permission under paragraph (1) transfers the facilities toanother person, or effects a succession, merger or division (limited to the case where said
equipment is succeeded to), the transferee who takes over such facilities, or the successor, thejuridical person who is the surviving juridical person, the juridical person who is newly
established after the merger or the juridical person who succeeds said equipment by division shallsucceed to the status of the person who has obtained permission of the same paragraph.
(4) A person who succeeds in accordance with the provisions of the preceding paragraph the status of
the person who has obtained permission under paragraph (1) shall without delay notify the
Minister of Internal Affairs and Communications with a document to prove that fact.
(5) The provisions of Article 14 paragraphs (1) and (2) (Certificates of Radio Station License),
Article 17 (Permission for Changes), Article 21 (Correction to a Certificate of Radio Station
License), Articles 22 and 23 (Abolition of a Radio Station), Article 24 (Return of a Certificate ofRadio Station License), Article 28 (Quality of Radio Waves), Article 30 (Safety Installation),
Article 38 (Technical Regulations), Article 72 (Cessation of Emission of Radio Waves), Article 73
paragraphs (4) and (6) (Inspection), Articles 76 and 77 (Revocation of a Radio Station License,etc.), and Article 81 (Report) shall apply, mutatis mutandis, to the facilities which has obtained
permission in accordance with the provisions of paragraph (1).

27

BWF TR-01(Protection of the Functions of Radio Equipment)
Article 101.
The provisions of Article 82 paragraph (1) shall apply, mutatis mutandis, to when the radio waves orhigh frequency currents emitted spuriously by any facilities other than radio equipment (except theequipment of the preceding article) cause successive and serious hindrances to the functions of radio
equipment.

28

BWF TR-01

Annex B (informative) Excerpt of related provisions of the Regulations for
Enforcement of the Radio Act
Chapter 3 High frequency-based equipment
Section 1 General Rules(Communication equipment)
Article 44
1. The communication equipment that does not require the permission prescribed in the Radio Act,
Article 100, Paragraph 1, Item 1 shall be as listed below:(i) Power line carrier communication equipment (which refers to power line carrier
communication equipment that performs communication by overlapping high-frequency
currents of 10 kHz or over on the power line; the same shall apply hereinafter.) as listed in thefollowing items:(1) Equipment that uses a power line flowing a single phased alternate current with a rated
voltage of 100V or 200V and a rated frequency of 50Hz or 60Hz, with its type specified by
the Minister for Internal Affairs and Communications.
(2)Equipment used solely for receiving purposes.
(ii) Inductive radio communication equipment (which refers to equipment that performs
communication by using inductive radio waves generated by flowing a high-frequency currentof 10 kHz or more to a power line; the same shall apply hereinafter.) as listed in the following
items:(1) The electric field strength in a distance of /2 from the power line (where,  is the
wavelength of the carrier wave in meters and  is the circular constant) is 15V/m or less.
(2) Inductive reading and writing radio communication equipment (which refers to equipmentthat reads and writes information in the recording media by using inductive radio waves witha frequency of 13.56 MHz; the same shall apply hereinafter.), whose electric field strength ina distance of three meters from the equipment is 500 microvolt or less per meter.
(3) Inductive reading and writing radio communication equipment whose type is specified by
the Minister for Internal Affairs and Communications
2. The specification by the Minister for Internal Affairs and Communications stipulated in Item 1-(1)of the preceding Paragraph shall be performed for each of the following classes.
(i) Power line carrier communication equipment listed below using a carrier wave with afrequency between 10 kHz and 450 kHz.
(1) Power carrying interphones (which refers to equipment that transmits/transfers and receives
voice signals; the same shall apply hereinafter.)(2) General power carrying digital transmission equipment (which refers to equipment that29

BWF TR-01

transmits/transfers and receives digital signals using a power line equipped with a blocking
filter with an attenuation of 40 decibels or more to prevent interference with othercommunication or a power line that is not branched to other equipment; the same shall apply
hereinafter.)(3) Special power carrying digital transmission equipment (which refers to equipment thattransmits/transfers and receives digital signals without limitation of the power line used; thesame shall apply hereinafter.)(ii) Power line carrier communication equipment transmitting/transferring and receiving signals
with a carrier wave with a frequency between 2 MHz and 30 MHz indoors (hereinafter referred
to as the “Broadband power line carrier communication equipment”).
(Equipment requiring permission, except communication equipment)
Article 45
The equipment using high-frequency current that requires permission under the Radio Act, Article
100, Paragraph 1, Item 2 shall be defined as follows:(i) Medical equipment (which refers to equipment that generates high frequency energy byusing a high frequency output of greater than 50W and uses the energy for medical purposes;
the same shall apply hereinafter.)(ii) Industrial heating equipment (which refers to equipment that generates high frequency
energy by using a high frequency output of greater than 50W and uses the energy forindustrial production such as drying of timber and plywood, drying of cocoon, melting of
metal, heating of metal, exhaust of vacuum tubes; the same shall apply hereinafter.)(iii) Miscellaneous equipment (which refers to equipment that is used for heating and ionizing
purposes by applying high-frequency energy to the load directly and that uses a highfrequency output of greater than 50W, [excluding the equipment falling under the categoriesof the preceding two Paragraphs, ultrasonic cleaners, ultrasonic processors and ultrasonicwelders with their types specified by the Minister for Internal Affairs and Communications,document printing and copying machines and electrodeless discharge lamps using
electromagnetic induction heating, and microwave ovens and electromagnetic induction
heating cookers for which type checks stipulated in Article 46 Paragraph 7 have been made];the same shall apply hereinafter.)30

BWF TR-01

Annex C (informative) Notification of the Ministry of Posts andTelecommunications, No. 301 of 1999
(Note: Table 2-2-2 in the Regulations for the Enforcement of the Radio Act referenced in thisnotification is changed to Table 2-3-2 as of April 2001.)

Radio wave strength at a frequency between over 10 kHz and 100 kHz or less and radio wave
strength in cases where the human body is exposed to a radio wave inhomogeneously, as stipulated
in the Regulations for Enforcement of the Radio Act, Appended Table 2, 2-2, Note 3 (April 27, 1999)(Notification of the Ministry of Posts and Telecommunications, No. 301)

Based on the regulation of the Regulations for Enforcement of the Radio Act (Radio Regulatory
Commission Rules No. 14 of 1950), Appended Table 2, 2-2, Note 3, radio wave strength at afrequency between over 10 kHz and 100 kHz or less and radio wave strength in cases where thehuman body is exposed to a radio wave inhomogeneously were specified as follows and came into
effect on October 1, 1999.

1. The strength of a frequency between over 10 kHz to 100 kHz or less shall conform to thefollowing in addition to the values specified in the Regulations for Enforcement of the Radio Act,
Appended Table 2, 2-2—except in cases where the human body is exposed to a radio wave
inhomogeneously.
Frequency
10 kHz < f  100
kHz

Electric field strength

Magnetic field strength

[V/m]

[A/m]

894

72.8

Average timeLess than one second

Note 1: The electric field strength and the magnetic field strength are the root mean square values.
Note 2: If multiple pieces of equipment in the same place or their periphery emit radio waves, or if
one piece of equipment emits multiple radio waves, the sum of the rates for the values in the table ofeach frequency must not exceed one.

2. The strength of a radio wave in cases where the human body is exposed to the radio wave
inhomogeneously is shown in Tables 1 and 2 below.

31

BWF TR-01

Frequency

Spatialaveragevalue ofelectric fieldstrength[V/m]

10 kHz < f  30 kHz
275
30 kHz < f  3 MHz
275
3 MHz < f  30 MHz
824f-130 MHz < f  300 MHz
27.5
300 MHz < f  1 GHz
1.585f1/2
1 GHz < f  1.5 GHz
1.585f1/2
1.5 GHz < f  300 GHz
61.4
Note 1: “f” denotes a frequency in MHz.

Table 1
Spatialaveragevalue ofmagnetic
field
strength[A/m]
72.8
2.18f-1
2.18f-1
0.0728f1/2/237.8
f1/2/237.8
0.163

Spatialaveragevalue ofpower flux
density[mW/cm2]

Spatialmaximum
value ofpower flux
density[mW/cm2)

0.2
f/1500f/1500
1

4
2
2

Averagetime[minutes]

6

Note 2: The electric field strength and the magnetic field strength are the root mean square values.
Note 3: If multiple pieces of equipment in the same place or their periphery emit radio waves, or if
one piece of equipment emits multiple radio waves, the squared-sum of the ratios for the values inthe table of each frequency must not exceed one for the electric strength and magnetic strength, andthe sum of the ratios for the values in the table for each frequency must not exceed one for the power
flux density.

Frequency
10 kHz < f  100 kHz

Table 2
Spatial average value
Spatial average valueof electric fieldof magnetic fieldstrength [V/m]strength [A/m]
894
72.8

Average timeLess than one second

Note 1: The electric field strength and the magnetic field strength are the root mean square values.
Note 2: If multiple pieces of equipment in the same place or their periphery emit radio waves, or if
one piece of equipment emits multiple radio waves, the sum of the ratios for the values in the tableof each frequency must not exceed one.

32

BWF TR-01

Annex D (informative) Notification of the Ministry of Posts andTelecommunications, No. 300 of 1999
Methods of calculating and measuring the strength of a radio wave that is emitted from wirelessequipment, pursuant to the Regulations for Enforcement of the Radio Act, Article 21, Paragraph 3,
Item 2(April 27, 1999)(Notification of the Ministry of Posts and Telecommunications, Number 300)

In pursuant to the Regulations for Enforcement of the Radio Act, Article 21, Paragraph 3, Item 2(Radio Regulatory Commission Rules No. 14 of 1950), the methods of calculating and measuring
the strength of a radio wave that is emitted from wireless equipment were stipulated as follows andcame into effect on October 1, 1999.

1. The meanings of the symbols in the formulas in this notification are as follows:(1) “E” is the electric field strength [V/m].
(2) “H” is the magnetic field strength [A/m].
(3) “S” is the power flux density [mW/cm2].
(4) “P” is the antenna input power (the value obtained by subtracting the power supply system loss
and the mismatch loss from the transmitter output; the same also applies hereinafter) [W]. For
pulse waves, it is the mean time of the antenna input power.
(5) “G” is the antenna absolute gain in the direction of the maximum radiated power of thetransmitting antenna indicated with by power ratio.
(6) “R” is the distance between the transmitting antenna pertaining to the calculation and thecalculation target position [m].
(7) “D” is the maximum size of the transmitting antenna [m].
(8) “” is the wavelength of the transmission frequency [m].
(9) “K” is the reflection coefficient; the following values should be assigned.
(A) When reflections from the ground are taken into account(a) When the transmission frequency is 76 MHz or more: 2.56(b) When the transmission frequency is less than 76 MHz: 4(B) When reflections from places other than the ground plane, such as the surface of water, aretaken into account: 4(C) When all reflections are not taken into account: 1(10) “F” is the correction coefficient due to the rotation of the antenna; the following values should
be assigned.
33

BWF TR-01(A) When the antenna is not rotating: 1(B) When the antenna is rotating:(a) When the distance R exceeds 0.6 D2/: BW/360“BW” is the half-power width [degree](b) When the distance R is 0.6 D2/ or less: /360“” is the expected angle [degree] of the antenna diameter in the distance R and = 2 tan-1 (D/2R)
2. To convert the power flux density into the electric field strength or magnetic field strength, use thefollowing formula.
S=E2/3770=37.7H2

3. The strength of the radio wave should be calculated for places where people who exist at eachazimuth of 45 degrees usually gather, pass, and enter/leave with respect to the direction of the
maximum radiated power from the position of the transmitting antenna pertaining to calculation. (Ifthe direction of its maximum radiated power is not determined, any direction is permitted.)
Calculation should be performed at points in intervals of at least /10[m] from the nearest point of
the transmitting antenna (hereinafter referred to as the “calculation point”). At each calculation point,
calculation should be performed at intervals of at least 10 cm (20 cm with a frequency of less than
300 MHz) in the range of 10 cm (20 cm with a frequency of less than 300 MHz) to 200 cm above theground plane to obtain the maximum value. Each calculation point must be apart from thetransmitting antenna and metal substance by at least 10 cm (20 cm with a frequency of less than 300
MHz).

4. If there is a building, steel tower, or metal structure, etc., near the calculation area and if there is
the danger of the occurrence of a strong reflection, add six decibels to the calculated radio wave
strength.

5. When calculating the strength of the radio wave, obtain the value of the power flux density fromthe following formula. For a frequency of 30 MHz or less, convert it to the value of the electric fieldstrength.
S=(PG/40R2)·K
6. When the calculation result using the method of Item 5 exceeds the strength of the radio wave
stipulated in the Regulations for Enforcement of the Radio Act, Appended Table 2, 2-2 (hereinafterreferred to as the “reference value”), and if the power directivity factor of the transmitting antenna D
34

BWF TR-01() is obvious, the strength of the radio waves should be obtained by obtaining the value of thepower flux density from the following formula. For a frequency of 30 MHz or less, convert it into
the value of the electric field strength.
S = S0·D()·F
Where, S0 is the value of the power flux density calculated using the method of Item 5.
Note 1: To obtain the value of the power flux density near the transmitting antenna in the direction
D()=0, make a calculation with the power directivity factor obtained by approximately representing
the directional characteristics of the antenna in question with the envelope (the line connecting the
local maximum values of the directional characteristics).
Note 2: If the calculation point is located outside the main radiation, the power directivity factor forthe calculation point in question may be calculated by using the power directivity factor for the
direction of the maximum sub-radiation.
Note 3: When an antenna on which two stages of elements are stacked is used in the radio equipment
for VHF or TV stations, calculation may be performed with the power directivity factor on thevertical plane as 0.1 at a depression angle of 45 degrees or more.

7. If both results calculated using the methods of Item 5 and Item 6 exceed the reference value, andif the type of the transmitting antenna falls under any of the following, the calculation method of theantenna in question should be used.
(1) Inside the main radiation of the collinear antenna array (which refers to an antenna that falls
under CL or SK of the antenna type basic code stipulated in the Notification of the Ministry of
Posts and Telecommunications, No. 148 of 1998, Appended Table 6-1 [hereinafter referred to as
the “antenna code”]), the strength of the radio wave when the distant R is 0.6 D2/ or less can beobtained by obtaining the value of the power flux density from the following formula. For afrequency of 30 MHz or less, convert it into the value of the electric field strength.
S = (P/20RD)·K
Note: For a sector-type antenna, calculate the strength using the following formula by utilizing thehalf-power width BW [degree].
S = (P/20RD)(360/BW)·K(2) For the strength of the radio wave on the surface or the main radiation direction of the apertureantenna (which refers to an antenna that falls under the antenna codes of PA, OP, FB, PG, HB, KG,
CR, HR, DH, BH, CH, TW, GG, DG, CG, TD, MB, H, PR, TO, or O), obtain the value of thepower flux density using the following method. For a frequency of 30 MHz or less, convert it into
the value of the electric field strength.
(A) Calculate the value of the power flux density on the surface of the antenna using the following
formula.
35

BWF TR-01

S = (4P/A)·(1/10)
Where, A is the aperture area of the aperture antenna [m2].
(B) When the distance R is D2/4 or less, calculate the value of the power flux density using thefollowing formula.
S = 16(P/D2)·(1/10)·K·F
Where,  is the aperture efficiency.
(C) When the distance R is greater than D2/4 and 0.6 D2/ or less, calculate the value of thepower flux density using the following formula.
S = (D2/4R)·Snf
Where, Snf is the value of the power flux density calculated from (B).
(3) For the strength of the radio wave of a monopole antenna for medium-wave broadcasting (whichrefers to an antenna that falls under the antenna code V or TL) in a range where the distance from theantenna is greater than both 2 D2/ [m] and /2 [m], obtain the values of the electric field strengthand magnetic field strength using the following formula.

Where, Ez, E, and H are the electric field strength and magnetic field strength of each direction
component at the calculation point P (, , z) shown in Appended Table 1. They can be calculatedusing the following formula.

Where, l is the total length of the circular tube [m],  is the radial coordinate [m] of the calculation
point, and z is the z coordinate [m] of the calculation point, as shown in Appended Table 1.
Where,“” is the angle frequency [rad/s];“0” is the magnetic permeability of the free space [H/m];“r” is the distance from the antenna [m];36

BWF TR-01“” is the z coordinate at any point on the antenna [m];“I0” is the current antinode [A];“ka” is the propagation constant on the antenna [rad/m];“k0” is the propagation constant in the free space [rad/m]; and“lt” is the equivalent total length of the antenna considering the influence of the top hat [m].
“I0,” “ka,” and “lt” should be obtained from the length of the antenna, the thickness of theantenna, and the size and the structure of the top hat.
(4) The strength of the radio wave by the curtain antenna (which refers to an antenna that falls under
the antenna code AW) should be calculated as follows.
(A) Depending on the distance from the transmitting antenna to the calculation point and its
frequency, the strength of the radio wave should be calculated as follows.
(a) When the calculation point from the nearest transmitting antenna is farther than both 2 D2/[m] and /2 [m], the electric field strength or the magnetic field strength should be
calculated. (For a frequency of 3 MHz or less, only the electric field strength should be
calculated.)(b) When the calculation point is other than (a), the electric field strength and magnetic fieldstrength should be calculated.
(B) When calculating the radio wave strength, regard each radiating element as an equivalent
half-wave dipole and calculate as follows.
(a) Calculate the strength of the radio wave by each equivalent half-wave dipole using thefollowing formula, obtain these composite values, and define them as the values of theelectric field strength and magnetic field strength at calculation point P (, , z), shown inAppended Figure 2.

Where,“” is the angle frequency [rad/s];“ko” is the propagation constant in the free space [rad/m]; and“0” is the dielectric constant in the free space [F/m].
37

BWF TR-01

The definitions of r1[m], r2[m], [m], z[m], Ez[V/m], E[V/m], and H[A/m] are shown inAppended Table 2.
“I” is an element current of the equivalent half-wave dipole and it is obtained by the antenna
power, the number of elements, and the input impedance of each element.
(b) When there is a reflector or when reflection from the ground is considered, consider thereflected image of the equivalent half-wave dipole for each case.
8. When the human body is exposed to a radio wave inhomogeneously (which refers to a case whereplaces exceeding the reference value and places not exceeding the reference value are mixed in anarea within 200 cm aboveground; the same also applies hereinafter), the strength of the radio waves
should be calculated by obtaining the special average value as shown below.
(1) For the power flux density, its average value(2) For the electric field strength and magnetic field strength, their root mean square value; for afrequency greater than 10 kHz but not greater than 100 kHz, the square root of their average value
and their root mean square value
9. When all of the calculation results using the methods from Item 5 to Item 8 exceed the reference
value, the strength of the radio wave must be measured. If such calculation result is defined as thestrength of the radio wave at the calculation point, no measurement is required.
10. Measure the strengths of the following radio waves.
(1) When the measurement point from the nearest transmitting antenna is farther than both 2 D2/[m] and /2 [m]:(A) For a frequency of 3 MHz or less, measure the electric field strength.
(B) For a frequency of greater than 3 MHz but not greater than 30 MHz, measure the electric fieldstrength or the magnetic field strength.
(C) For a frequency exceeding 30 MHz, measure the electric field strength, magnetic fieldstrength, or power flux density.
(2) When the measurement point is other than (1):
(A) For a frequency of 1,000 MHz or less, measure the electric field strength and magnetic fieldstrength.
(B) For a frequency exceeding 1,000 MHz, measure the electric field strength.

11. For measurement, use the following instruments.
(1) Isotopic electromagnetic field probe(2) Frequency non-tunable measurement system (which refers to an antenna for measurement or afrequency non-tunable measurement instrument that responds to the strengths of radio waves
uniformly over a wide range of frequencies; the same also applies hereinafter)(3) Frequency tunable measurement system (which refers to an antenna for measurement or a38

BWF TR-01

frequency tunable measurement instrument that tunes to a specific frequency and mainly responds toradio waves in the band centering on the frequency; the same also applies hereinafter)

12 The conditions of the measurement systems are as follows.
(1) Isotopic electromagnetic field probe(A) In the range of frequencies that the wireless equipment under measurement can emit, thefluctuation of values should be within three decibels when the probe is turned to an arbitrary
angle or to an arbitrary direction.
(B) In the range of frequencies that the wireless equipment under measurement can emit, thefrequency characteristics of values measured in the same strength of radio waves should be flat.
In addition, the response of the measurement instrument to frequencies outside the frequency
range of radio waves is obvious.
(C) In the range of frequencies that the wireless equipment under measurement can emit, the rangeof the strengths of the radio waves that can be measured should be obvious. In addition, theelectric field probe should respond only to the electric field. The magnetic field probe should
respond only to the magnetic field.
(D) Attached cables should not affect measurement.
(E) The response time should be less than one second.

(2) Frequency tunable/non-tunable measurement systems(A) The frequency range that can be measured by the instrument, the frequency resolution band
width (in the frequency tunable measurement system), the input sensitivity, the detecting
method, and the maxim permissible input should be known.
(B) Depending on the characteristics of radio waves emitted from the wireless equipment undermeasurement, an appropriate antenna with a known antenna coefficient should be used.
(C) The input impedance of the antenna for measurement and the measurement instrument should
be appropriate for the measurement cable.
(D) Sufficient electromagnetic shielding should be provided for the measurement instrument andcable.
(E) Necessary action should be taken so that the equipment under measurement is not affected byradio waves emitted from that other than the equipment under measurement.
13 Method of measuring the strength of a radio wave
(1) The strength of the radio wave should be measured using the following method.
(A) Measure the maximum value of the strength of the radio wave by scanning the range between
10 cm (20 cm with a frequency of less than 300 MHz) and 200 cm above the measurement
point vertically with an isotopic electromagnetic field probe or an antenna for measurement.
39

BWF TR-01

Note that the electromagnetic field probe or the antenna for measurement should be 10 cm or
more (20 cm or more with a frequency of less than 300 MHz) from the transmitting antenna, theground, and the metal substance.
(B) When the strength of the radio wave changes with time, define the strength of the radio wave
obtained using the following method as the measurement value.
(a) For the power flux density, it is the average of the values measured for six minutes.
(b) For the electric field strength and magnetic field strength, they are the root mean square of
the values measured for six minutes. In the frequency range between over 10 kHz and 100
kHz or less, it is the square root of their maximum value and the root mean square of values
measured for six minutes.
Note: If the average of measurements for six minutes can be obtained in a period less than six
minutes due to the modulation characteristics of radio waves emitted from the radio equipment undermeasurement, the measurement time may be shortened as required.
(2) For the strength of radio waves when the human body is exposed to a radio wave
inhomogeneously, it is possible to measure the strength in intervals of 10 cm (20 cm with afrequency of less than 300 MHz) from 10 cm (20 cm with a frequency of less than 300 MHz) to 200
cm above the measurement point and to obtain its spatial average value in accordance with themethod in Section 8.
(3) When making a measurement, note the following points.
(A) Place the antenna for measurement so that its direction and plane polarization maximize its
reading.
(B) If one of the antennas for measurement and the transmitting antenna produces a circularly
polarized wave and if the other produces a linearly polarized wave, add three decibels to themeasurement value as the correction value.
(C) When vertically scanning the electromagnetic field probe or the antenna for measurement,
hold it so that influence on the human body and polarization is minimized.
(D) To measure the pulse wave, use a thermocouple-type electromagnetic field probe, a frequency
non-tunable measurement system, or a frequency tunable measurement system having afrequency resolution band that is wider than the band occupied by the pulses.
(E) If the influence of radio waves emitted from other radio equipment cannot be ignored, use afrequency tunable measurement system.

40

BWF TR-01

Appended Table 1
The coordinate system and formula symbols of the calculation formula stipulated in Section 7 (3) are

Length of the circular tube

Equivalent length of the circular tube

shown in the following figure.

Calculation point

Appended Table 2
The coordinate system and formula symbols of the calculation formula stipulated in Section 7 (4) are
shown in the following figure

Center of the half-wave
dipoleCalculation
point

41

BWF TR-01

Annex E (informative) Safety measures against heat or other causes
1．Safety measures against heat or other causes
・ Temperature rise limits for the components comprising the transmission side and reception
side shall be below 35 K for metals, 45 K for porcelains or glasses, and 60 K for molded
products, rubber, and wood. (The base temperature for the above temperature rise limits is
25°C.)
・ When a temperature rise limit is exceeded, take a measure such as power transmission stop.
No restrictions are specified for power supply.
Note: See IEC 60335-1 “Household and similar electrical appliances – Safety – Part 1: General
requirements 11. Temperature rise.”・ The above limits are also applied to any metallic alien substance piece located between thetransmission side and the reception side.
・ Devices and parts used for the equipment shall cause no smoke or fire when an abnormal
condition occurs.

2．Measurement method for the temperature rise of a metallic alien substance located between
the transmission side and the reception side
As a safety measure for the case where a metal piece is located between the transmission side andthe reception side, the following procedure shall be carried out to measure a temperature rise,
ensuring that the requirements described in section 8.2.2 are satisfied.
(1) Measure the temperature rise of metals including iron, aluminum, and copper.
(2) Test piece
A test piece is determined in the following way, using the equipment comprising thetransmission side and the reception side (when more than one reception side exists, select the one
with the highest load power), with the transmit coil and the receive coil facing.
・ At the center of the coil:-Prepare a metal piece that measures 5 mm long, 5 mm wide, and 0.3 mm thick, and thentry another one with its width and length increased in increments of 1 mm until the largest
42

BWF TR-01

piece that maintains the normal operation of the equipment is found,*1 naming it “testpiece (1).”-Repeat the same steps as above starting with two pieces of metal having a thickness of 0.5mm and 1.0 mm, in order to find the largest piece that maintains the normal operation of
the equipment,*1 naming each “test piece (2)” and “test piece (3),” respectively. Note thatthe largest piece shall fit in the power transmission coil or coil plane completely.

・ Out of the center of the coil:-

Repeat the same steps as above starting with three pieces of metal, measuring 5 by 5 by
0.3 millimeters, then try another one with its width and length increased in increments of
1 mm until the largest piece that maintains the normal operation of the equipment is found,naming it “test piece (4).” In case of having a thickness of 0.5 mm and 1.0 mm, in order tofind the largest piece, name each “test piece (5)” and “test piece (6),” respectively.

*1

Normal operation refers to the one that lets the equipment achieve its given functions. Placing
a metal piece between the transmission side and the reception side during operation could
generate heat, leading to reduced safety. If the equipment achieves its given functions
under this circumstance, it is under normal operation.

(3) Evaluation method-

Test pieces (1) to (6) are used for evaluation.

-

Experiments are conducted under the same condition as the one where each test piece wasdetermined in the above (2).

-The equipment (transmission side and reception side) are operated with a thermocouple
connected to the test piece.

-

The highest temperature before the saturated temperature is reached is taken as a test piecetemperature. When the equipment stops operating before the saturated temperature is reached,
the highest temperature before the stop of the equipment is taken as a test piece temperature.
When the equipment is forced to stop due to its metal detection ability or temperature sensing
ability, the highest temperature before the stop of the equipment is taken as a test piecetemperature.

-

A thermocouple with a thickness of 0.3 mm or lower is used so that a test piece is least
affected by it (conforming to IEC 60335-1).
43

BWF TR-01

Annex F (informative) Explanation of radio-radiation protection guidelines
In the field of wireless power transmission/transfer technologies, it is believed that the guideline
values for electromagnetic field exposure are often required to be followed, and these are stipulated in
the domestic guidelines in Japan, or in the ICNIRP or IEEE internationally. However, since theseguidelines may be revised reflecting the results of a study that has been continuously conducted from ascientific or epidemiologic point of view, the latest information has to be continuously checked.
The ICNIRP, which has revised the guidelines for the low-frequency range on November 2010, hasalready set out to revise guidelines for the high-frequency range, and is planning to release these new
guidelines around 2014. For an evaluation method in accordance with the new guidelines, IEC TC106
is conducting the international standardization of the common evaluation method for theelectromagnetic field exposure, but the method assumed to be used for the equipment described in thepresent guidelines has not yet been released.
In the domestic guidelines, on the other hand, the guideline values and their evaluation andmeasurement method are defined, but they are slightly different with the ICNIRP guideline values,
evaluation method by the IEC TC106, or the IEEE guidelines. This results from the time lag between
the discussion periods of these guidelines. Under the circumstances, the domestic guidelines can berevised considering the international trends.
In this discussion, based on the fact that the domestic guidelines differ from the internationalguidelines (that is, ICNIRP guidelines and IEEE standards), we put high priority on the domestic
guidelines, presenting the ICNIRP guidelines as opposite to them. We also give an explanation about
the IEEE guidelines.
The domestic guidelines presents, when his/her body is exposed to an electromagnetic field for radio
wave use, the basic methods and reference values to determine whether the electromagnetic field issafe without producing an undesirable electromagnetic effect (core body temperature rise, electricalshock, high-frequency radio wave burn, etc.) on the human body, how to measure and estimate theelectromagnetic field strength on the perimeter of the radio utilization facilities, and a protection
method to reduce the strength of the electromagnetic field radiated to the human body, providing theguidelines for determining the safety standards, advisories, and operating procedures for the use ofradio waves.
The ICNIRP, on the other hand, describes a direct or indirect coupling mechanism between theelectromagnetic field and the human body, a direct or indirect effect of the electromagnetic field on
the human body, and the biological grounds for the restrictions of the electromagnetic field exposure.
Based on them, it stipulates the guidelines for the restrictions, including the restrictions ofoccupational/public exposure, the basic restrictions, and the reference levels. The ICNIRP, which
presents the restriction value of the exposure in its guidelines, leaves it to other international
44

BWF TR-01

organizations regarding how to implement a measurement method for the exposure.
In the following discussion, we mainly explain the radio-radiation protection guidelines, keeping it
in mind that, although the domestic guidelines and the ICNIRP guidelines are stipulated based on thecommon ideas, there are differences between them in their guideline values for the low-frequency
range. The terminologies for ICNIRP are also specified, enclosed in double quotes, throughout thediscussion.

There is a basic rule for evaluating the safety of the human body based on various biological effects
caused in the human body under exposure to an electromagnetic field, and the guidelines for such iscalled the “basic restrictions.” However, since it is difficult to directly measure whether the basic
restrictions are met, the administrative guidelines, defined using the actual measurable physicalamount, are used for actual evaluation. The “reference level” is one of the administrative guidelines.
If the radiation source is located at a sufficiently distant location and if there is no metal or otherobject that scatters radio waves at a place close to the space in which the human body exists, it canbe assumed that the electromagnetic phenomenon inside the human body in the space bears analmost constant relation to the electric field strength and the magnetic field strength measured when
the human body does not exist in said space. Under such a condition, protection guidelines can be set
by using the electromagnetic field strength in a space in which no human body exists. This guidelineis called the “electromagnetic field strength guidelines.” The electromagnetic field strength is ameasurable physical amount. As the electromagnetic field covered by the protection guideline isusually a near-field type or in an inhomogeneous location, the electromagnetic field strength
guideline cannot apply, as many states exist. In an electromagnetic environment that does not meetthe requirements for the application of the guidelines, there are cases where evaluation only of thespace is not appropriate. In the case where the electromagnetic field strength guideline cannot beapplied as-is, the supplementary guidelines are provided. The supplementary guideline is a
simplified evaluation method for the electromagnetic phenomenon inside the human body, as analternative to the basic guidelines. Therefore, it is necessary to bear in mind that the evaluation basedon the basic guidelines should always be considered when the supplementary guidelines cannot beapplied.

45

BWF TR-01

Basic guidelines
Whole-body
average SAR

Induced current
density

Contact
current

Local incident
power (in the eye)

Local average
SAR

Grounds ↓↑Strict evaluation

Administrative guidelines
Electromagnetic
field strength
guidelines

Supplementary
guidelines

Partial bodyabsorption
guidelines

Generalenvironm
ent

Guidelines forwhen the humanbody exposure is
inhomogeneouslyor partially

Generalenvironm
ent

Guidelines forcontact current
Controlledenvironme
nt

Guidelines for
induced ankle
current

Controlledenvironme
nt

Fig. 8.3.1 Overview of the radio-radiation protection guidelines

The supplementary guideline values for the strength of a radio wave in cases where the human bodyis exposed to a radio wave inhomogeneously are stipulated in the notification of the Ministry of
Posts and Telecommunications, No. 301 (released on April 27, 1999), shown in Annex C. Also, thecalculation and measurement method for the strength of a radio wave radiated from wirelessequipment is stipulated in the notification of the Ministry of Posts and Telecommunications, No. 300(released on April 27, 1999), shown in Annex D. The excerpts from the domestic guideline values,
the ICNIRP guideline values, and the IEEE guideline values are shown below in Table F-1, Table
F-2, and Table F-3, respectively.

46

BWF TR-01

F-1．Excerpts from the domestic guidelines(1) Guidelines concerning stimulant effect
The electromagnetic field strength guideline shown in the table below should be referred to in thefrequency range of 10 kHz to 100 kHz. Note that in the case where the electromagnetic field isinhomogeneous or where the human body becomes within 20 cm of the equipment in normal use,the following restriction values can be exceeded without exceeding the basic restrictions. This caseis described in section (3).
Table F-1: Limit values associated with stimulant action
Frequency

Spatial average of

Spatial average ofelectric fieldmagnetic fieldstrength ［V/m］

strength ［A/m］

894

72.8

10 kHz < f  100 kHz

Average timeLess than 1 second

Note 1: The electric field strength and the magnetic field strength are the root mean square values.
Note 2: If multiple radiation sources of equipment in the same place or their periphery emit radio
waves, or if one piece of equipment emits multiple radio waves, the squared-sum of the ratio of
each electric strength or magnetic strength (which is the spatial average value) to the guideline value
for the corresponding frequency in the table must not exceed one.

(2) Guidelines concerning thermal effect
When the equipment is large enough to cover a whole human body, the whole-body average SAR
evaluation is appropriate, while when the exposure can be regarded as partial, the local average SAR
evaluation is appropriate. Note that since the SAR evaluation in the frequency range below 30 MHz
has not yet been established, it is desirable to evaluate the exposure using the guideline values shownin the table below.

Table F-2: Exposure limit values associated with thermal action
Frequency

Spatial average Spatial average of Spatial average

Averageof electric fieldmagnetic fieldvalue of power

timestrength

strength ［A/m］

flux density［minute］［V/m］[mW/cm2]

10 kHz < f  30 kHz

275

72.8

30 kHz < f  3 MHz

275

2.18f－1

47

6

BWF TR-01

3 MHz < f  30 MHz

824f－1

2.18f－1

30 MHz < f  300 MHz

27.5

0.07280.2

Note 1: “f” denotes a frequency in MHz.
Note 2: The electric field strength and the magnetic field strength are the root mean square values.
Note 3: If multiple radiation sources of equipment in the same place or in their periphery emit
radio waves, or if one piece of equipment emits multiple radio waves, the squared-sum of the ratio of
each electric strength or magnetic strength (which is the spatial average value) to the guideline value
for the corresponding frequency in the table must not exceed one; or the sum of the ratio of eachpower flux density (which is the spatial average value) to the guideline value for the corresponding
frequency in the table must not exceed one.
(For reference) The attached sheet 1 of the normative reference [6] stipulates the following
supplementary guidelines.
Supplementary guidelines (1): Guidelines for when the human body is exposed to anelectromagnetic field inhomogeneously or partially
Administrative guidelines are considered to be satisfied when the appropriate
requirements, varying depending on frequency, are all satisfied.
Note that for the equipment used within 20 cm of the human body (for a frequency
range higher than 300 MHz, within 10 cm of the human body), a decision on acase-by-case basis is required. If it is anticipated that the basic guideline values can beexceeded, an evaluation based on the partial body absorption guidelines isrecommended<1> For the frequency range below 300 MHz
In a space more than 20 cm away from the electromagnetic radiation source and metal
substance, the spatial average of the power density distribution in the space that thehuman body occupies (for the electric field strength and magnetic field strength, theirroot mean square value)(3) Guidelines concerning contact current
In the domestic guidelines, the supplementary guidelines (2) quoted below are stipulated.
Supplementary guidelines (2): Guidelines concerning contact current
48

BWF TR-01(b) In the case where contact hazard cannot be prevented in the general environment
A contact current measured in the frequency range of 10 kHz to 100 kHz is not higher
than 4.5×10-4f[Hz]mA (with an average time of less than 1 second), and a contact
current measured in the frequency range of 100 kHz to 15 MHz is not higher than 45
mA (with an average time of six minutes).
Note that, when it is not clear if a contact current caused by multiple frequencies cannot
be neglected under this guideline, the squared-sum of the ratio of each measured value
to the guideline value of the corresponding frequencies should be obtained. Thissquared-sum shall not exceed 1.

(4) Guidelines concerning induced current
In the domestic guidelines, the supplementary guidelines (3) quoted below may be followed.
Supplementary guidelines (3): Guidelines concerning induced ankle current(b) In the case where an ungrounded condition is not satisfied in the general environment
An induced ankle current measured in the frequency range of 3 MHz to 300 MHz is nothigher than 45 mA (with an average time of six minutes) per one foot.
Note that, when an induced current caused by multiple frequency components cannot be
neglected under this guideline, the squared-sum of the ratio of each measured value tothe guideline value of the corresponding frequency component should be obtained. Thissquared-sum shall not exceed 1.
Note:
The Report of the Telecommunications Technology Council (November 1998): Inquiry No. 104,
Chapter 2 of “The methods of measuring and calculating the strength of the radio wave to checkthe conformity to the radio-radiation protection guidelines” describes the reasons why the
associated measurement methods are not subject to any public regulation including notifications asfollows.
The radio-radiation protection guidelines applied are the electromagnetic field strength guidelines
and supplementary guidelines in the general environment. The supplementary guidelines for
induced or contact current, however, which are desirable to be used as private guidelines as before,
are not subject to any public regulation for radio-radiation protection for the reasons shown below.
(ARIB STD-38 etc.)49

BWF TR-01(1) The measurement method or equipment is not well established for induced current or contact
current.
(2) For the guideline values for induced current, there is no reasonable definition for an
ungrounded condition of the human body, and it is very difficult to decide whether thecondition, even if it is reasonably defined, is satisfied or not.
(3) The guideline values for contact current, which are based on the sensing thresholds, are not
the levels beyond which human health is immediately affected.
(4) Electric fields equal in strength could cause a different level of current to flow into thehuman body depending on how large the metal substance to be measured is, making it
impossible to constantly determine the electromagnetic field strength in terms of contact
current.
(5) In the United States or Australia, where public regulation has already been introduced or isconsidered to be introduced, there are no restrictions on contact or induced current.

50

BWF TR-01

F-2．Excerpts from the ICNIRP guideline values
The reference levels defined in the 1998 and 2010 edition of the ICNIRP guidelines are shown in thetable below. Note that the frequency range brackets are overlapped between the 1998 edition and the2010 edition.

Table F-3: Reference levels defined in the ICNIRP guidelines (1998 and 2010 edition)
Note: “f” in the 2010 edition denotes a frequency in Hz; “F” in the 1998 edition denotes afrequency in the unit specified in the “Ranges of frequency” column.
Electric field

Magnetic fieldcharacteri

strength

strengthstics（kV/m）（A/m）

Public exposure

Occupational exposure

Exposure Ranges of frequency

Magnetic flux density Equivalentplane wave（μT）
power density(W/㎡)

1 Hz–8 Hz

2010

20

1.63×105 / f2

0.2 / f2

8 Hz–25 Hz

edition20

2×104 / f

2.5×10-2 / f

25 Hz–300 Hz

5×102 / f

8×102

1×10-3300 Hz–3 kHz

5×102 / f

2.4×105 / f

0.3 / f

3 kHz–10 MHz

1.7×10-1

80

1×10-4Up to 1 MHz

1998

610×10-3

1.6 / F

2.0 / F-

1 MHz–10 MHz

edition610×10-3 / F

1.6 / F

2.0 / F-

10 MHz–400 MHz

61

0.16

0.2

10

400 MHz–2,000 MHz

3 F1/20.008 F1/2

0.01 F1/2

F / 402 GHz–300 GHz

137

0.36

0.45

50

1 Hz–8 Hz

2010

5

3.2×104 / f2

4×10-2 / f2

8 Hz–25 Hz

edition5

4×103 / f

5×10-3 / f

25 Hz–50 Hz

5

1.6×102

2×10-450 Hz–400 Hz

2.5×102 / f

1.6×102

2×10-4400 Hz–3 kHz

2.5×102 / f

6.4×104 / f

8×10-2 / f

3 kHz–10 MHz

8.3×10-2

21

2.7×10-5

Up to 1 MHz

1998

87×10-3

0.73 / F

0.92 / F-

1 MHz–10 MHz

edition87 / F1/2

0.73 / F

0.92 / F-

10 MHz–400 MHz

27.5

0.073

0.092

2

400 MHz–2,000 MHz

1.375 F1/2

0.0037 F1/2

0.0046 F1/2

F / 200

2 GHz–300 GHz

61

0.16

0.20

10

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F-3. Excerpts from the IEEE guideline values

The IEEE guidelines are the guidelines based on a consensus established through open scientificdiscussions in the United States. The IEEE, for which the precursor had been actively working on theissue of electromagnetic field exposure from the earliest time globally, now develops the guidelines
and technology standards for the exposure from the viewpoint of biological effects at the ICES
(International Committee on Electromagnetic Safety) TC95, a private organization of the IEEE. The
following series have been released to date.

IEEE std C95.1-2005 3 kHz–300 GHz Safe levels with respect to electromagnetic field
exposure
IEEE std C95.6-2002 0 kHz –3 kHz

Safe levels with respect to electromagnetic field

exposure
IEEE std 1528-2003 SAR measurement method (1 g or 10 g)
IEEE std C95.3-2010 SAR
The exposure evaluation methods through numerical calculation (1528.1 – 4) are currently being
standardized under the dual logo agreement between IEC TC106 and the IEEE ICES TC34.

The IEEE Std. C95.1-2005 stipulates the basic restrictions (BR) and maximum permissive exposure(MPE) of stimulant action and thermal action, in the frequency range of 3 kHz to 5 MHz and 100 kHz
to 300 GHz, respectively. This means that, in the frequency range of 100 kHz to 5 MHz, both stimulant
action and thermal action are required to be considered. Also, in stimulant action, the exposure low induty cycle has a higher restriction value.

Table F-4: Basic restrictions (BR) in parts of the human body

Level of action

Exposure in a limited environment(= public exposure)(= occupational exposure)fe (Hz)E0 (effective value) (V/m)

E0 (effective value) (V/m)

Brain

20

5.89 x 10-3

1.77 x 10-2

Heart

167

0.943

0.943

Hand, wrist, leg, ankle

3350

2.10

2.10

Other parts

3350

0.701

2.10

Parts of the body to be
exposed52

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Table F-5: Maximum permissive exposure (MPE) associated with stimulant effect in the frequency
range of 3 kHz to 5 MHz

Level of action

Exposure in a limited environment

Head, Extremity Head, torso Extremity Head, torso Extremity Head, torso Extremity
torsoFrequency range

B effectie value

H effective value (A/m) B effective value (mT) H effective value (A/m)(mT)
3.0–3.35 kHz

0.687/f

3.79/f

547/f

3016/f2.06/f3.79/f

1640/f

3016/f3.35 kHz–5 MHz

0.205

1.13

163

900

0.615

1.13

490

900

Table F-6: Maximum permissive exposure (MPE) associated with an external electric field in thefrequency range of 3 kHz to 100 kHz

Frequency range

Level of action

Exposure in a limited environment

3 kHz–100 kHz

614

1842

In the case where the external electric field is inhomogeneous to the human body, the special averageof the electric field shall not be higher than the limits shown in Table F-5.
In a limited environment, when the human body is not within the reach of grounded conductive
material, the restrictions shown in Table F-5 may be exceeded. In that case, no restrictions are defined.
In any circumstances, the basic restrictions shown in Table F-4 and the contact current limits shown in
Table F-7 cannot be exceeded.

Table F-7: Limits of induced and contact current in the frequency range of 3 kHz to 100 kHz (effective
values)Condition

Level of action

Exposure in a limited environment

Both feet

0.90f

2.00 f

One foot

0.45f

1.00 fContact (gripping)—1.00 f0.167f0.50 f(When trained in a limited
environment)
Contact

The above limits are applied to a current that flows between the human body and a grounded object.
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The average time shall be 0.2 seconds.

Table F-8: Basic restrictions (BR) associated with thermal action in the frequency range of 100 kHz to
3 GHz

Level of action

Exposure in a limited environment

SAR (W/kg)*

SAR (W/kg)*

Whole body average (WBA)

0.08

0.4

Partial body

Partial body exposure (peak

2**

10**

exposure

spatial-average)
4**

20**

Whole body
exposure

Extremity and auricle* SAR is an average over six minutes.
** An average per a tissue mass of 10 g (a cubic tissue mass of approximately 10 cubic centimeters)

Table F-9: Limits of induced and contact current in the frequency range of 100 kHz to 110 MHz(effective values)

Condition

Level of action

Exposure in a limited environment

(mA)

(mA)

Both feet

90

200

One foot

45

100

Contact (gripping)

—

100

16.7

50

(When trained in a limited
environment)
Contact

Table F-10: Maximum permissive exposure (MPE) associated with thermal action in the frequency
range of 100 kHz to 300 GHz(MPE, public)

Ranges ofEffective

Effective value of Effective value of magnetic flux

frequency

value ofmagnetic fielddensity (S)electric fieldstrength (H)Electric field, magnetic fieldstrength (E)(A/m)*(W/m2)

54

Average time**|E|2, |H|2, or S (minutes)

BWF TR-01(V/m)*
614

16.3/fM(1000, 100 000/fM2) *c

6

6823.8/fM

16.3/fM(1800/fM2, 100 000/fM2)

fM2/0.3

6

3–30 MHz

823.8/fM

16.3/fM(1800/fM2, 100 000/fM2)30

630–10027.5

158.3/fM1.668(2, 9 400 000/fM3.336)

30

0.0636 fM1.337

27.5

0.0729

2

30

30

-

-

fM/20030

2–5 GHz

-

-

10

30

5–30 GHz--10150/fG

30–100--1025.24/fG0.476--(90fG–7000)/200

5048/[(9fG–700)fG0.476]

0.1–1.34
MHz
1.34–3MHzMHz
100–400
MHz
400–2,000
MHzGHz
100–300
GHz

Notes: fM denotes a frequency in MHz, while fG denotes a frequency in GHz.
* The table shows the MPE values for the electromagnetic field strength and power density for thecase of homogeneous exposure throughout the entire body in far-field radiation.
In an inhomogeneous exposure, an average of the exposure field is taken. The averaging is done byaveraging the power density or the square of the electromagnetic field strength throughout a narrow
area depending on frequency or the vertical section (projected area) of the human body.
** The left and right column of the average time column shows the average time of |E|2 and |H|2,
respectively. The average time column with the frequency equal to or higher than 400 MHz shows
the average time of S.

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Annex G (informative) Examples of exposure calculation
Examples of exposure calculation considering basic restrictions are shown below as reference.
Document 1: Yuki Isaka, Yuuhei Kubo, and Masao Taki, “Dosimetry and transfer characteristic ofwireless transfer system of magnetic resonant coupling, ,” IEICE Society Conference，B-4-11，
2011．
This abstract, assuming a power transmission between two coils (200 x 200, five turns) placed 100
mm away from each other, describes an analysis of SAR distributions in the case where the system isplaced at the feet of the human body. The resonant frequency is about 20 MHz. The finite-differencetime-domain (FDTD) method is used for the analysis.

Document 2: A. Christ, M.G. Douglas, J.M. Roman, E.B. Cooper, A.P. Sample, B.H. Waters, J. R.
Smith, and N. Kuster, “Evaluation of Wireless Resonant Power Transfer Systems with Human
Electromagnetic Exposure Limits,” IEEE Trans. on Electromagnetic Compatibility, vol. 55, no. 2, pp.
265–274, 2013.
This paper, assuming a power transmission between two spiral coils (305 mm inside diameter, 580
mm outside diameter, 6.1 turns, 10-mm pitch, 2.54-mm wire diameter), describes an analysis of SAR
in the case where a numerical human body model is located nearby. The resonant frequency is about
8 MHz. FDTD is used for analysis. First, an incident electromagnetic field generated only from thetransmission side is calculated. Then, assuming that a Huygens box is present in the space that thehuman body occupies, a scattered electromagnetic field to the incident electromagnetic field
generated due to the presence of the human body is analyzed, obtaining an electromagnetic field andSAR inside the human body. To examine an experimental evaluation method for SAR, another SAR
analysis is also performed for the case where a cylindrical model is present near the coil.

Document 3: Ilkka Laakso, Shogo Tsuchida, Akimasa Hirata, and Yoshitsugu Kamimura,“Evaluation of SAR in a human body model due to wireless power transmission in the 10-MHz
range,” Physics in Medicine and Biology, vol. 57, no. 15, pp. 4,991–5,002, 2012.
This paper, assuming power transmission between two solenoidal coils (300-mm diameter, 5 turns,
2-mm wire diameter) placed 300 mm away from each other, describes an analysis of SAR in the casewhere a numerical human body model is located nearby. The resonant frequency is about 10 MHz.
First, an electromagnetic field at the periphery of the system is calculated through the Moment
method. Then, a magnetic vector potential is obtained assuming that the current distribution in thecoil does not change due to the presence of the human body. With that value, the electric field56

BWF TR-01

distribution inside the human body is analyzed through the Scalar Potential Finite Difference (SPFD)
method.
Document 4: S.W. Park. K. Wake, and S. Watanabe, “Investigation of Numerical Methods andDosimetry for a Wireless Power Transfer System Using Electromagnetic Resonance,” International
Symposium on Electromagnetic Compatibility, 2012.
This abstract, assuming a power transmission between two solenoidal coils (300-mm diameter, 5.45
turns) placed one meter away from each other, describes an analysis of SAR and the inductive
electric field inside the human body in the case where a numerical human body model is locatednearby. The resonant frequency is about 10 MHz. First, an electromagnetic field at the periphery of
the system is calculated through the Moment method. Then, an analysis is performed with theresulting electromagnetic field regarded as the incident electromagnetic field, assuming that thecurrent distribution in the coil does not change due to the presence of the human body. In theanalysis, the amount of the induced field is compared in two different cases. Firstly, the FDTD
method is used to analyze the induced electric field inside the human body with both the incident
electric field and the incident magnetic field being taken into account. Next, the Impedance method
is used with only the incident magnetic field being taken into account, in order to compare bothresults.
Document 5: Yuuhei Kubo and Masao Taki, “Interaction of wireless power transfer and human bodyusing resonators with coupled electric fields,” IEICE Society Conference, B-4-12, 2011．
This abstract, assuming power transmission of a coupled electric field type with two 50-mm squareplates facing each other, 10 mm apart, describes an analysis of SAR and the inductive electric field
inside the human body in the case where the human body is located nearby. The resonant frequency
is about 9 MHz. The Finite-difference Time-domain (FDTD) method is used for the analysis.

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Appendix 1. Wireless power transmission beyond 50 W
This appendix describes a technology not covered in edition 2.0 of the guideline, which could becovered in the future through technology developments, improvements in institutionalization, andstandardization.

We take the example of a wireless power transmission/transfer of 50 W or higher using thefrequency range beyond 10 kHz, shown in usage scenes 3, 4, and 5 in Table 6-1 “Wireless powertransmission/transfer technology usage scenes.” The status of this technology at the time of thiswriting (April 2013), the regulations applied to it, and technical problems are as follows.

1.

Status of the technology at the time of this writing (guideline 2.0)

The wireless power transmission/transfer of 50 W or higher using a frequency range beyond 10 kHz
has not been put into full-fledged practical use, being used only for the experiment or test operationof the battery charging for electric vehicles or for the demonstration of the wireless charging ofhome electrical appliances such as TVs at trade shows, etc.

2.

Regulations applied
The regulation for a high-frequency wave utilizing facilities as stipulated in the Radio Act isapplied to this technology.
According to the Radio Act, Article 100, Paragraph 1, any person who wishes to install a facility
that uses high-frequency currents of 10 kHz or above shall obtain permission for that facility from
the Minister of Internal Affairs and Communications. Also, according to the same article, Paragraph
2, the Minister of Internal Affairs and Communications shall permit the construction in theapplication when determining that the application satisfies the required technical regulations and thatthe use of frequencies related to the application causes no interference with other communications(See Annex A)
The facilities requiring the above permission are actually stipulated in the enforcement regulationof the Radio Act, while wireless power transmission facilities other than communication equipment
fall under the categories specified in the Radio Act, Article 45, Paragraph 3, stipulating that
equipment that uses a high-frequency output of greater than 50 W requires permission (see Annex B).
Also, as technical standards for a high-frequency utilizing facility other than communicationequipment, the acceptable values for the electromagnetic field strength are stipulated in Article 65 of
the wireless equipment regulations, while interference preventions, etc., are stipulated in Article 66of the same regulation.
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Thus, although installing a wireless power transmission/transfer equipment of 50 W or higher
requires applying for the above permission, once the permission application is accepted, theequipment can be installed and operated.

3.

Technical problems
The following technical problems are required to be solved, depending on the characteristics ofeach product.
(1) Selection of a frequency that does not interfere with other equipment(2) Establishment of an evaluation method for a leakage of electromagnetic field(3) Development and employment of interference-reducing technology(4) Establishment of an evaluation method for protecting the human body against radio radiation(5) Development and employment of radio radiation protection methods and other safety measures

4.

Standardization trend

For wireless power transmission/transfer used for electric vehicles categorized in the usage scene 4,
discussions are now being conducted to establish the following standards in the U.S.A. and theworld.
(1) SAE J2954: (U.S.A.) Wireless Charging of Plug-in Vehicles and Positioning Communication(2) UL2750: (U.S.A.) Wireless charging safety (Draft: SU2750)(3) IEC61980 series: (International)a)IEC61980-1: Electric vehicle wireless power transfer (WPT) systems – General
requirementsb)

IEC61980-2: Electric vehicle wireless power transfer (WPT) systems – Specificrequirements for communication between electric road vehicle (EV) and infrastructurewith respect to wireless power transfer (WPT) systemsc)

IEC61980-3: Electric vehicle wireless power transfer (WPT) systems – Specificrequirements for the magnetic field power transfer systems

Note:

SAE (Society of Automotive Engineers International)
UL (Underwriters Laboratories)

59

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Reference Standards
JIS C 9335-1 Household and similar electrical appliances - Safety - Part 1: General requirements
RCR STD-38 Edition 2.0, ARIB standard “Radiofrequency-exposure Protection Standard”
ARIB TR-T11 Edition 1.0, ARIB technical report “Methods of Evaluating Compliance for theRadiofrequency-exposure Protection Standard”

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GUIDELINES FOR THE USE OF WIRELESS POWER TRANSMISSION/TRANSFERTECHNOLOGIES TECHNICAL REPORTBWF TR-01 Edition 2.0

This document is a translation into English of the approved document for the purpose of
convenience of users.
If there are any discrepancies in the content, expressions, etc., between the Japaneseoriginal and this translated document, the Japanese original shall prevail.

Release of Electronic Version: May 2013, Edition 2.0
Issued from Broadband Wireless Forum, YRP R&D Promotion Committee
Contact: YRP R&D Promotion Committee Secretariat
Address: YRP Center No. 1 Bldg. 3-4 Hikarinooka, Yokosuka , Kanagawa, Japan 239-0847
Tel: +81-46-847-5399
Fax: +81-46-847-5010

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