Special Issue

Challenges to New Technologies and New Products

The EMI Characteristics of the Electric Field Resonance Type
Wireless Power Transfer System
Daiki Obara*, Hiroyuki Yamazaki*, Mitsuru Masuda*

The Wireless Power Transfer (WPT) has been drawing the attention as a technology for charging an electric vehicle and a mobile equipment in a non-contact
manner. Since the WPT system utilizes the high-frequency power, there is a concern related tothe interference to the broadcasting and the wireless communication due to the unnecessary
radiated emission, etc. Therefore, except for some systems, it is necessary to satisfy the ElectroMagnetic Interference (EMI) allowable value of the high frequency utilization equipment in accordance with the Article 65 of the Radio Equipment Regulation and to obtain the installation permit.
We have developed the electric field resonance type WPT system with a frequency of 13.56 MHz
and an output power of 1 kW that satisfies the EMI allowable value specified for the high frequency utilization equipment and have obtained the installation permit.
In this paper we will report the various characteristics of this system.

ABSTRACTINTRODUCTION
1.1. INTRODUCTION
The research on the WPT has been actively conducted asa technology for charging an electric vehicle and a mobile
equipment in a non-contact manner without connecting a
power cable. Particularly, since the electrification of theautomobile is progressing with the background of the
global energy problem, the expectation of the WPT to theelectric vehicles is also growing. In Japan, the institutionalization of the WPT for the electric vehicle has been promoted ahead of the rest of the world and the development has been very active.
In this paper, we will explain the status of the institutionalization and the standardization of the WPT system,
especially for the Radio Law high frequency utilizationequipment in Japan and also will report the characteristics of the developed electric field resonance type WPTsystem, the EMI measurement result, etc.

ABOUTTHE
THEINSTITUTIONIZATIONINSTITUTIONIZATION AND
2.2. ABOUT
AND
THE
STANDARDIZATION
OF
THE
WPT
THE STANDARDIZATION
THE WPT
2.1

The Status of the Standardization of the EMC
Regulation
The WPT system has been discussed also at CISPR (anInternational Radio Interference Special Committee; anorganization that works for the international standardization of the specifications in area such as the ElectroMagnetic Compatibility (EMC) measurement method and*Automotive Products & Electronics Laboratories, R & D Division

the allowable value of the wireless equipment.). In CISPR,
the WPT system is regarded as the Industrial, Scientificand Medical (ISM) equipment and the revision of theinternational standard CISPR 11 that defines the EMI
measurement method of the ISM equipment and theallowable value is under way.
2.2 The Status of the Institutionalization in Japan
2.2.1 The legal position of the WPT system
In Japan, based on the Article 100 of the Radio Law, theequipment corresponding to the following is deemed to
be a high frequency utilization equipment and it is stipulated to obtain the permit from the Ministry of Internal
Affairs and Communications Minister before installing theequipment.
1) The telegraph, the telephone and the other communication equipment that passes a high frequency currentof 10 kHz or more to the electric line.
2) The industrial heating equipment, the medical equipment and the various equipment utilizing a high frequency current of 10 kHz or more (the equipment otherthan the communication).
In these equipment, an unnecessary radiated emission
and a conducted noise occur due to the use of a high frequency current and may interfere with the broadcasting
and the wireless communication so that the installation
permit is required. The WPT system is no exception andthe WPT system using a radio wave of 50 W or more (10kHz or more and less than 3 THz) requires the permit to
install the high frequency utilization equipment in accordance with the Article 45 of the Radio Law Enforcement
Regulation. The WPT system for the mobile equipment,
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The EMI Characteristics of the Electric Field Resonance Type Wireless Power Transfer System

etc. is also regarded as a high frequency utilization equipment, but the installation permit is not required if thetransmission power is 50 W or less.
In Japan, the institutionalization of the WPT is being
advanced ahead of the rest of the world. The Ministry ofInternal Affairs and Communications Ordinance No. 15
dated March 15, 2016 was promulgated and enforced
and the ministerial ordinance revision of the Article 45, 46of the Enforcement Regulation of the Radio Law, etc. wasmade. The following WPT equipment for the general purpose and the non-contact power transfer equipment for
the electric vehicle are newly added as the equipmentthat can designate the type of the high frequency utilization equipment.
• “400 kHz band electric field coupling type non-contact
power transfer equipment for the general purpose”• “6.7 MHz band magnetic field coupling type non-contact power transfer equipment for the general purpose”• “non-contact power transfer equipment for the electricvehicle”

However, in order to receive these type designations, inaccordance with the Ministry of Internal Affairs andCommunications Public Notice No. 69 to 71 in 2016, it isnecessary to adapt to the criteria for the measurement
method of the conducted noise emission and the unnecessary radiated emission, the safety equipment for theradio wave intensity, etc. Figure 1 shows the legal position of these WPT systems. If these type designations
can be received, the individual application for the installation will be unnecessary so that it is expected to be widely sold, utilized and popularized. In the future, it is thoughtthat the institutionalization will also expand for the WPTsystems applied to the industrial equipment such as a
rapid charging, a large power for the electric buses, an
Automated Guided Vehicle (AGV) and etc.

Equipment requiring thepermit in the high frequency
utilization equipment.
Communication equipment
Telegraph, telephone and othercommunication equipment that uses
a high frequency current of 10 kHz or more
Article 100, Paragraph 1,
Item 1 of the Radio Law

Equipment other thancommunication equipment
50 W or more
Use a high frequency current of 10 kHz or more

Medical equipment
Industrial heating equipment

Various equipment

13.56 MHz,
1 kW electric field resonance type WPTFrequency

13.56
MHz

Electric
field

OutputPower1000 W

Article 100, Paragraph 1, Item 2 of the Radio Law
Article 45 of the Radio Law Enforcement Regulation

Type confirmation
No need for the individual
installation permit

Equipment not requiring thepermit in the high frequency
utilization equipment
Communication equipment

Microwave

Power carrier wave communicationequipment (reception only)

Electro-magnetic induction
heating (IH) cooker

Inductive communication equipment

Article 46-7 of the Radio Law Enforcement Regulation

Type designation
No need for the individual
installation permit
Power transfer wave communicationequipment, etc.
Revision of the Radio Law Enforcement Regulation
Ministerial Ordinance dated March 15, 2016
(The Ministry of Internal Affairs andCommunications Ordinance No. 15 in 2016)

400 kHz band electric field
coupling typenon-contact power transfer
equipment for the general purpose

Equipment other thancommunication equipment
50 W or less
Medical equipment
Industrial heating equipment
Various equipment

WPT

6.7 MHz band magnetic
field coupling typenon-contact power transfer
equipment for the general purpose
Non-contact power 85 MHz band
Max. 7.7 kW
transfer equipment
for the electric vehicle
Article 46-2 of the Radio Law Enforcement Regulation

Figure 1 The legal position of the WPT system.

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The EMI Characteristics of the Electric Field Resonance Type Wireless Power Transfer System

THEDEVELOPMENTDEVELOPMENT OF
OF THETHE ELECTRIC
3.3. THE
ELECTRICFIELDRESONANCERESONANCE TYPE
TYPE COUPLER
FIELDCOUPLER
3.1

The Features of the Electric Field Coupling TypeWPT
For the coupler structure of the electric field coupling
type WPT, a meander line shape1), a flat plate electrodeplate shape2) and etc. are studied. Since a meander line
shape utilizes the resonance due to the inductance andthe capacitance of the pattern itself, it is unnecessary to
add an inductance and a planar structure can be taken.
However, due to the length of the transmission line andthe pattern structure, the loss in the high frequency band
increases under the influence of the skin effect and theproximity effect when the high frequency current.is flowing. On the other hand, when a flat plate electrode isused, it is necessary to add an inductance such as a resonance coil, etc., but a pattern like the meander line isunnecessary and the loss in the high frequency band canbe reduced.
In addition, in the electric field coupling type WPT,
which positively utilizes the resonance, a high voltage is
generated using the resonance and conversely the current can be reduced. As a result, the electrode material
can be constructed using an inexpensive metal material
such as aluminum, iron, etc. having a lower electricalconductivity than copper.
3.2 About the Electric Field Resonance Type
Coupler3), 4)
3.2.1 The structure of the electric field resonancetype coupler
We are developing the electric field resonance type coupler using a flat plate electrode and a resonance coil. The
coupler has a series resonance structure in which a plateelectrode and a resonance coil are connected in series.
Each of the power transmission side coupler and thepower reception side coupler is designed to resonate at a
specific frequency by itself. This coupler is named as theelectric field resonance type coupler because the couplers having the same resonance frequency are used inpairs. Figure 2 and Figure 3 show a schematic view andan equivalent circuit diagram of the coupler. The structureof the coupler itself is a very simple structure.

Zs

L

L

ｗ

ｗ

C

C

Zo

Coupler
Figure 3 The equivalent circuit diagram of the electric fieldresonance type coupler.

The radiated noise is one of the problems of the electricfield resonance type coupler WPT. Figure 4 shows thestate of the electric lines of force extending around theelectric field resonance type coupler as an example of theelectromagnetic field analysis. In this way, since the electric field is a divergence field, the electric lines of force
extend to the surroundings and couples with the structurearound the coupler and the ground.so that the leakage
electric field is easily generated. Therefore, a common
mode loop through the earth occurs and the generationof the unintended radiated noise becomes a problem.

Electorode
coil
Erectric
field

Load

RF generator

Figure 4 The state of the electric lines of force occurringaround the electric field resonance type coupler.

Figure 2 The schematic view of the electric field resonancetype coupler.

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The EMI Characteristics of the Electric Field Resonance Type Wireless Power Transfer System

MHz. Since the consistency is obtained at that frequency
and there is almost no reflection loss, it means that theinsertion loss of 7.4% is generated. Most of this loss
appears as a heat generated in the coil. Since the coiluses an air core solenoid coil and there is no iron loss
due to the ferrite material, etc., the copper loss of the coilitself and the high frequency loss are considered to be
the main factors. In order to further improve the efficiencyof the electric field resonance type coupler, it is necessary
to reduce the loss of the coil portion.
1
0.9

η21

0.8

η11

0.7
0.6
η21,η11

One method of preventing this is to enclose the coupler
with a metallic shield box having an aperture. An unnecessary coupling with the surroundings can be prevented
by the shield box. On the other hand, since the coupling
between the coupler and the shield becomes stronger,
the coupling between the transmission and the reception
becomes weak so that the problem that the transmission
distance becomes short will occur.
3.2.2 The transmission properties of the electric fieldresonance type coupler
The external view of the developed electric field resonance type coupler is shown in Figure 5. In order to suppress the unnecessary coupling with the surroundings, a
coupler is placed in a metallic shield box provided with anaperture. Table 1 shows the specifications of the electricfield resonance type coupler. The electrode size and thenumber of turns of the coil are adjusted to resonate at afrequency of 13.56 MHz.

0.5
0.4

W

0.3
0.2

L

0.1

Electrode

0

coil

10

11

12

13
14
15
Frequency[MHz]

16

17

18

Figure 6 The frequency characteristics of the transmission
efficiency and the reflection loss of the electric fieldresonance type coupler.

D
Shield box
Figure 5 The external view of the electric field resonance type
coupler with a shield box.

Table 1The specifications for the electric field resonancetype coupler.
Item

Specification value

Frequency

13.56 MHz

Characteristic impedance

50 Ω

Distance between couplers

77 mm

External dimensions

L480 x W180 x D80 mm

Volume18.4 litter

The frequency characteristics of the electric field resonance type coupler were measured using a network analyzer (Agilent Technologies, E 5061 B). Figure 6 shows thefrequency characteristics of the transmission efficiency η
21 (= |S21|2) and the reflection loss η 11 (= |S11|2) measured using the network analyzer (Agilent Technologies, E
5061 B). From this, it can be understood that the hightransmission efficiency of 92.6% is shown at the distanceof 77 mm between couplers and a frequency of 13.56

THEACQUISITIONACQUISITION OF THE
4.4. THETHE INSTALLATIONINSTALLATIONPERMITFORFORTHETHE HIGH
HIGH FREQENCYPERMIT
FREQENCY UTILIUTILIZATIONEQUIPMENTOF THEELECTRICZATIONEQUIPMENTOF THEELECTRICFIELDRESONANCERESONANCE TYPE
TYPE WPTFIELD
WPTSYSTEMSYSTEM
4.1

The Specifications for the Electric Field
Resonance Type WPT System
The WPT system shown in Figure 7 was constructed withthe aim of obtaining the installation permit of the high frequency utilization equipment of the electric field resonance type WPT system operating at a frequency of
13.56 MHz and an output power of 1 kW. The photographof the external view and the specifications of the WPTsystem constructed are shown in Figure 8 and Table 2.

High
frequency
power
supplyElectric
field
resonance
type coupler

50Ω load

Figure 7 The block of the electric field resonance type WPTsystem.

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The EMI Characteristics of the Electric Field Resonance Type Wireless Power Transfer System

Figure 8 The external view of the electric field resonance type
WPT system.

Table 2The specifications of the electric field resonance type
WPT system.
Item

Specification value

Frequency

13.56 MHz

Transmitted power

1 kW

Distance between couplers

77 mm

4.2

About the Legal Status of the Electric Field
Resonance Type WPT System With a Frequencyof 13.56 MHz and an Output Power of 1 kW
From the Ministry of Internal Affairs and Communications
Notification No. 207 dated June 11, 2015, the special
provisions on the allowable value of the EMI are stipulated for the high frequency utilization equipment other thanthe communication equipment in accordance with the
Article 65, Paragraph 1 of the Radio Equipment
Regulation. Within the following frequency bands, themaximum allowable value of the noise terminal voltage,
and the magnetic field intensity and the electric field
intensity due to the radiation and the unintended radiatedemissions is not defined.
• 13.56 MHz ± 6.78 kHz• 27.12 MHz ± 126.72 kHz• 40.68 MHz ± 20.34 kHz• 2450 MHz ± 50 MHz• 5.8 GHz ± 75 MHz• 24.125 GHz ± 125 MHz
Table 3

These frequencies correspond to the ISM band inJapan and are frequency bands allocated for the general
purpose in the industrial, scientific and medical fields.
The regulations on the radio interference, the electromagnetic compatibility and etc., are relaxed.
As shown in Figure 1, since the electric field resonancetype WPT system with a frequency of 13.56 MHz and an
output power of 1 kW falls under the high frequency utilization equipment, it is necessary to satisfy the allowablevalue of the EMI in accordance with the Article 65,
Paragraph 1, Item 4 of the Radio Equipment Regulation.
However, since the fundamental frequency of 13.56 MHz
and its harmonic frequency of 27.12 MHz and 40.68 MHz
are included in the ISM band and the maximum allowablevalue is not defined, it is necessary to satisfy the abovementioned allowable value of the EMI excluding these frequencies.
4.3 The EMI Measurement of the Electric Field
Resonance Type WPT System
In order to obtain the permit for the installation of the highfrequency utilization equipment, the EMI measurement
shall be carried out at the certified site of the EMI test to
indicate that the allowable value is satisfied. It is necessary to carry out the EMI measurement of the radiatednoise and the conducted noise as a performance verification test of the high frequency utilization equipment regulation.
We conducted the EMI measurements at the certified
site based on the domestic standards5) in compliancewith the international standard CISPR 11 version 5.1.
Table 3 shows the EMI measurement conditions of theperformance verification test of the high frequency utilization equipment regulations. These measurement results
are shown in Figure 9 to Figure 16. For each measurement result, the allowable value in accordance with the
Article 65, Paragraph 1, Item 4 of the Radio Equipment
Regulation and as a reference, the allowable value of the
ISM band equipment Class A Group 2 specified by
CISPR 11 are noted together. Equipment Class A Group 2
is intended for the utilization in an industrial environment
and is an ISM RF equipment that intentionally generates
and uses the radio frequency energy.
Figure 9 shows the state of the magnetic field intensity
measurement using a loop antenna. The magnetic field
intensity was measured at a separation distance of 10 m

The conditions for the EMI measurement.

Conducted
noise

Radiatednoise

Measuring equipment

Lower limit
frequency

Upper limit
frequency

Detection
mode

Measuring
environment

Measurement target

Unit

Conducted noise
emission

dBuV

LISN

150 kHz

30 MHzAV

Shielded room

dBuV

LISN

150 kHz

30 MHzQP

Shielded room

Magnetic field intensity

dBuA/mLoop antenna

150 kHz

30 MHz

QP

Anechoic chamber,
10 m separation

Electric field intensity

dBuV/mBiconical antenna

30 MHz300 MHz

QP

Anechoic chamber,
10 m separation

Electric field intensity

dBuV/m

Log-periodic antenna

300 MHz

1000 MHz

QP

Anechoic chamber,
10 m separation

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The EMI Characteristics of the Electric Field Resonance Type Wireless Power Transfer System

between the antenna and the Equipment Under Test
(EUT) and a frequency of 150 kHz - 30 MHz. Figure 10
shows the chart data of the magnetic field intensity measurement result and the allowable value of the QP value(quasi-peak value detection). The chart data shows themeasurement results of the QP value and PK value (peakvalue detection) for each rotation angle of the loop antenna (0, 45, 90, 135 deg.; for the convenience of the data
display, data of the 135 deg. are not described here,).
Peaks are seen at the fundamental frequency of 13.56
MHz and the second harmonic frequency of 27.12 MHz,but these are excluded because they are included in the
ISM band. It is understood that the magnetic field intensity is suppressed sufficiently low against the allowablevalue. In addition, strictly speaking, in the magnetic field
intensity measurement, it is necessary to rotate the turn
table on which the EUT is placed for each rotation angleof the loop antenna, to find the condition that maximizes
the magnetic field intensity, to acquire the point data, andto show that the point data does not exceed the allowable value. In this measurement, it is confirmed that the
point data also does not exceed the allowable value.

Loopantenna

EUT
Figure 9 The state of the magnetic field intensity measurement
using a loop antenna (measurement distance; 10 m).

Limit1（QP）

Field Strength [dBμA/m]

70
60
50
40
30
20
10
0
-10
-20
-30
.2
.15

Figure 11 shows the state of the electric field intensity
measurement using a biconical antenna and a log-periodic antenna. The electric field intensity measurement was
performed at a separation distance of 10 m between theantenna and the EUT and at a frequency of 30 - 1000
MHz. As explained in Section 3.2.1, the electric field resonance type WPT easily couples with the surrounding
structure and it becomes an antenna even at an unintended frequency so that the radiated noise becomes aproblem. Figure 12 shows the chart data of the electricfield intensity measurement result and the allowable valueof the QP value when the measures for the radiated noise
are insufficient. The chart data show the measurement
results of the QP value and the PK value for each rotation
direction of the antenna (horizontal direction, verticaldirection). Many peaks of the odd-order multiple harmonic waves of 13.56 MHz, which is the fundamental frequency, can be seen. Also, in the band of 200 MHz or
more, it can be understood that many peaks exist at thefrequencies other than the harmonic components. This is
the noise due to the common mode current caused by
the unintended coupling. In the electric field resonancetype WPT, it is necessary to take sufficient measuresagainst such unnecessary radiated emission. Figure 13
shows the electric field intensity measurement result after
the measures for the noise. Although the peaks of the
odd-order multiple harmonics wave of 13.56 MHz, whichis the fundamental frequency, can be seen, it can beunderstood that it does not exceed the allowable value(The third harmonic wave 40.68 MHz is excluded because
it is included in the ISM band.). In addition, many peaks,
which exist even in the band of 200 MHz or more, disappeared and it can be understood that the unnecessary
radiated emission was suppressed. In addition, strictly
speaking, in the electric field intensity measurement, it isnecessary to rotate the turn table on which the EUT isplaced and to change the height of the antenna, to findthe condition that maximizes the electric field intensity, toacquire the point data and to show that the point data
does not exceeded the allowable value. In this measurement result, it is confirmed that the point data also does
not exceed the allowable value.

1st 13.56MHz

Limit2（QP）
0deg
（PK）
0deg
（QP）
45deg
（PK）
45deg
（QP）
90deg
（PK）
90deg
（QP）

2nd 27.12MHz

.3

.5 .7

1
2 3
5
Frequency [MHz]

7 10

20

30

Figure 10 The result of the radiated noise.
Magnetic field intensity measurement (150 kHz - 30 MHz)
Limit 1: R adio Equipment Regulations Article 65,
Paragraph 1, Item 4 (2) I 10 m
Limit 2: CISPR 11 Group 2 Class A 10 m

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The EMI Characteristics of the Electric Field Resonance Type Wireless Power Transfer System

Biconical
antenna

Log-periodic
antenna

EUT

Field Strength [dBμV/m]

Figure 11 The state of the electric field intensity measurement
using a biconical antenna and a log-periodic antenna(measurement distance 10 m).

80
75
70
65
5th 67.8MHz
60
55 rd 40.68MHz
50 3
45
40
35
30
25
20
9th 122.0MHz15
7th 94.9MHz
10
5
0

30

50

70

100
200 300
Frequency [MHz]Figure 14 shows the status of the conducted noise
emissions measurement using the LISN. The conducted
noise emissions measurement was performed at thepower supply terminal at the frequency of 150 kHz - 30
MHz. Since the single-phase power supply is used in thismeasurement, L phase (Live ungrounded side) and N
phase (Neutral grounded side) measurements are performed. Figure 15 and Figure 16 show the chart data ofthe measurement results of the conducted noise emissions and the allowable value of the QP value and the AV
value (average value detection). The chart data show themeasurement results of the QP value and the AV value.
Peaks are seen at the fundamental frequency of 13.56
MHz and the second harmonic of 27.12 MHz, but theseare excluded because they are included in the ISM band.
It can be understood that the conducted noise emissions
are suppressed sufficiently lower than the allowablevalue. In this measurement also, it is confirmed that theallowable value is not exceeded in the point data.

Limit1（QP）

Limit2（QP）

EUT

Hori.（PK）
Hori.（QP）
Vert.（PK）
Vert.（QP）

500 700

LISN

1000

80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0

30

Limit1（QP）

Figure 14 The status of the conducted noise emissions
measurement using a line impedance stabilization
network (LISN).

Limit2（QP）
Hori.（PK）
Hori.（QP）
Vert.（PK）
Vert.（QP）

3rd 40.68MHz
5th 67.8MHz
7th 94.9MHz
9th 122.0MHz
50

70

100
200 300
Frequency [MHz]

110
100
90
80
70
60
50
40
30
20
10
0

1st 13.56MHz

500 700

1000

Figure 13 The radiated noise measurement result after themeasures for the radiated noise.
The electric field intensity measurement (30 – 1000 MHz)
Limit 1: R adio Equipment Regulation Article 65 (1) Item(iv) (3) 10 m
Limit 2: C ISPR 11 Group 2 Class A 10 m

.15

Limit1（QP）
Limit2（AV）

N（PK）
N（QP/AV）
L1（PK）
L1（QP/AV）

Level [dBμV]

Field Strength [dBμV/m]

Figure 12 The radiated noise measurement result before themeasures for the radiated noise.
Electric field intensity measurement (30 – 1000 MHz)
Limit 1: R adio Equipment Regulations Article 65,
Paragraph 1, Item 4 (3) 10 m
Limit 2: C ISPR 11 Group 2 Class A 10 m

2nd 27.12MHz
.2

.3

.5 .7

1
2 3
5 7 10Frequency [MHz]20

30

Figure 15 The measurement result of the conducted noise
emissions. Interference wave voltage measurement at
the power supply terminal (150 kHz - 30 MHz)
Limit 1: R adio Equipment Regulation Article 65,
Paragraph 1, Item 4 (1) QP(20 kVA or less)
Limit 2: R adio Equipment Regulations Article 65 (1) (iv)
(1) AV

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The EMI Characteristics of the Electric Field Resonance Type Wireless Power Transfer System

1st 13.56MHz.15

Limit1（QP）

CONCLUSION
5.5. CONCLUSION

N（PK）
N（QP/AV）
L1（PK）
L1（QP/AV）The EMI measurement of the electric field resonance type
WPT system with a frequency of 13.56 MHz and an output power of 1 kW was carried out. We were able to confirm the ability to satisfy the EMI allowable value specified
by the high frequency utilization equipment. We submitted this measurement result together with the permit
application form of the high frequency utilization equipment and we were able to obtain the installation permit of
the high frequency utilization equipment.

Limit2（AV）

Level [dBμV]

110
100
90
80
70
60
50
40
30
20
10
0

2nd 27.12MHz
.2 .3

.5 .7

1
2 3
5 7 10Frequency [MHz]20

30

Figure 16 The measurement result of the conducted noise
emissions .
Limit 1: CISPR 11 Group 2 Class A QP
Limit 2: CISPR 11 Group 2 Class A AV

From the above results, it can be understood that eachnoise value in accordance with the Article 65, Paragraph
1, Item 4 of the Radio Equipment Regulation is below theallowable value of the EMI except for the ISM band. We
were able to confirm the ability that the developed electric field resonance type WPT system with a frequency of
13.56 MHz and an output power of 1 kW satisfies thehigh frequency utilization equipment regulations.

REFERENCE
1) Takehiro Imura: “Study on the magnetic field coupling and the electric field coupling of the non-contact power transfer viewed fromthe equivalent circuit WTP utilizing the electromagnetic field coupling at a resonance”, Journal of the Institute of ElectricalEngineers of Japan, D, Vol. 130, No. 1, (2010), pp. 84-92.
2) Kenichi Harakawa: “The Electric Field Coupling / Resonance TypeWPT Technology - Parallel resonance type power transfer analysis”,
Technical Information of the Institute of Electronics, Information
and Communication Engineers, WPT 2011- 24, (2011)
3) Mitsuru Masuda: “The Electric Field Resonance Coupling TypeWPT System”, Technical Information of the Institute of Electronics,
Information and Communication Engineers, WPT 2013-20, (2013)
4) Mitsuru Masuda: Furukawa Electric Review, 137, (2018), p 20-27
5) Advisory No. 3 “About the various standards of the International
Radio Interference Special Committee (CISPR)” “The allowablevalue and the measurement method of the interference waves fromthe industrial, scientific and medical equipment” findings

Furukawa Electric Review, No. 50 201926