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Current Research and Development ofWireless Power Transfer via Radio Waves
and the Application [DML]
Apr. 7, 2017
Naoki Shinohara, Professor,
Research Institute for Sustainable Humanosphere, Kyoto University
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Copyright© The use of this work is restricted solely for academic purposes. The author of this work owns the copyright and no reproduction in any form is permitted without written permission by the author.
2
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AbstractTheory, technologies, applications, and current R&D status of the wireless power transfer (WPT) will be presented. The talk will cover both the far-field WPT via radio waves, especially beam-type and ubiquitous-type WPT, and energy harvesting from broadcasting waves. The research of the WPT was started from the far-field WPT via radio waves, in particular the microwaves in 1960s. In recent years this became a hot topic again due to the rapid growth of wireless devices. Theory and technologies of antenna and circuits will be presented in case of beam-type and ubiquitous-type WPT. The industrial applications and current R&D status of the WPT via radio waves will be also presented.
Index Terms: Wireless Power Transfer, Microwave Power Transmission, Energy Harvesting, Rectenna, Phased Array,
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BiographyNaoki Shinohara received the B.E. degree in electronic engineering, the M.E. and Ph.D (Eng.) degrees in electrical engineering from KyotoUniversity, Japan, in 1991, 1993 and 1996, respectively. He was aresearch associate in the Radio Atmospheric Science Center, KyotoUniversity from 1996. From 2010, he has been a professor in ResearchInstitute for Sustainable Humanosphere, Kyoto University. He has beenengaged in research on Solar Power Station/Satellite and MicrowavePower Transmission system. He is IEEE Distinguish Microwave Lecturer,IEEE MTT-S Technical Committee 26 (Wireless Power Transfer andConversion) vice chair, IEEE MTT-S Kansai Chapter TPC member, IEEEWireless Power Transfer Conference advisory committee member,international journal of Wireless Power Transfer (Cambridge Press)executive editor, Radio Science for URSI Japanese committee Cmember, , past technical committee chair on IEICE Wireless PowerTransfer, Japan Society of Electromagnetic Wave Energy Applicationsvice chair, Wireless Power Transfer Consortium for PracticalApplications (WiPoT) chair, and Wireless Power ManagementConsortium (WPMc) chair. 4
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Kyoto and Kyoto University
5
KyotoWinter
Autumn
Spring APMC2018 will be held at Kyoto.
- Kyoto Univ. Data (2015) -
Professors : 1,032 (5,445 Employees)
Students : 13,569 (Under Graduate)
4,773 (Master), 3,671 (Ph.D)
Novel Prizes (Prof. Yamanaka, Prof. Yukawa,
Prof. Tomonaga, Prof. Tonegawa, Prof. Fukui..)
Main Campus
Uji Campus
Kyoto Univ.
Kyoto Univ.
Tokyo
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RISH, Kyoto Univ.
Microwave Power Transmission Field Experiment in Kyoto Univ.
1993
Second MPT
Rocket
Experiment
- ISY-METS -
1994-95
Ground-to-Ground
MPT Experiment
1996
Retrodirective
MPT System
Open Experiment
1983
First MPT Rocket Experiment
In the World - MINIX-1992
MPT Experiment to
Fuel-free Airplane
- MILAX -
2001
Solar Power
Radio Integrated
Transmitter
- SPRITZ -
2009
Airship-to-Ground
MPT Experiment
6
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Contents1. Overview of Wireless Power Transfer via Radio Waves2. Current R&D of WPT via Radio Waves3. Theory and technology of WPT via Radio Waves4. Introduction of Activities of WPT in IEEE5. Conclusion
7SHARP Airplane exp.
1987@CanadaMPT to helicopter
By W. Brown 1964, 1968MPT rocket exp.
1983 by Kyoto Univ., ISAS
Island-Island MPT (150km)in Hawaii2008 by Kobe Univ., NASA
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8
Overview of Wireless Power Transfer
via Radio Waves
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Utilization of Radio Waves
• Information, Broadcast :Information added (modulated) on carrier
(radio waves) (Information from transmitter)• Radar (Remote Sensing) :
Information (amplitude, phase, etc.) reflectedfrom target on carrier (Information from target)
• Heating :Energy conversion from radio waves to heat
• Power Transfer :Energy conversion from radio waves to electricity(Frequency conversion only form GHz(MHz) to AC/DC)
All Radio Waves, Light, and Electricity are
based on Maxwell’s Equations.
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Various Wireless Power Transfer
I
I
H
Supply
User
I
I
H
Supply
User
L
L
C
C
Resonance of L and C
Transmitter
Transmitted
Power
Receiver
→PowerOnly Carrier for WPT
Very Narrow
Electric Power
To User
Frequency
Time and
Space
Inductive
Coupling
(Magnetic)
Resonance
Coupling
Capacitive
Coupling
10
E
V
V
Radio Waves
(Microwaves)
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WPT Theory
Faraday’s law :
NS
Load
High
Frequency
Ampere’s law : H
IδH
NS
Coil
Electromagnetic Wave
(Radio Wave)Electric Field Electric Field
Magnetic FieldMagnetic Field
High
Frequency
Transmitting
AntennaReceiving
Antenna
Raidowave Power (Electric Power)Maxwell’s Equations
Inductive Coupling WPT
WPT via Radio Waves
H
0
Bdiv
Ddiv
t
BErot
t
DJHrot
11
)/( 2mW
HES
Radio wave itself is energy.
What we need is frequency conversion only.
Electromagnet
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Brief History of WPT• 1864 Prediction of Radio Waves by establishment of
Maxwell’s Equation based on Ampere’s law andFaraday’s law. (Radio waves was found in 1888 byHertz’s experiment)
• Around 1900 Tesla carried out WPT experiment ofboth inductive WPT and WPT via radio wave (150kHz),-> faired
• 1960s W. Brown carried out beam-type WPT viamicrowave (2.45GHz) -> succeeded
• 1980s Commercial Products of inductive WPT (Shaver,IC card..)
• 1990s 1) RF-ID, 2) RF WPT toward Solar Power Satellitein Japan
• 2006 MIT group proposed resonance coupling WPT(revised inductive coupling)
• 2010s Various WPT – Standardization of inductiveWPT, wireless charger for EV, energy harvesting frombroadcasting waves, ubiquitous RF-WPT…
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Current R&D of WPT via Radio Waves
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Various Wireless Power Transfer via Radio Waves(a) Beam-type
(High efficiency with higher frequency)
(b)Ubiquitous-type (Low efficiency, like RF-ID)
(c) Energy Harvesting
(No power source)
Transmitter
Receiver
→Power
Time and Space
Information
Frequency
Wide
Electric Power
to User Receiver
→Power
Transmitted
Power
Transmitted
Power
Transmitted
Power
Transmitter
Transmitted
Power (Broad)
→ Electric
PowerOnly Carrier for WPT
Very Narrow
Frequency
Time and
Space
→ Electric
Power→ Electric
Power
14
(d) In Closed Area (like Waveguide)
Transmitter
Transmitted Power
Receiver→
Power
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Power Density of TV/Mobile Phone in Nara, Japan
15Kitazawa, S., et al., “Field Test Results of RF Energy Harvesting from
Cellular Base Station”, Proc. of GSMM2013
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Kanazawa Inst. Tech., “The 500MHz band low power rectennafor DTV in the Tokyo area”, Proc. of WPTc2016
16
Frequency plan at Tokyo area
Center
frequencyERP
TV
Stations
491MHz 11.5 kW MX
521MHz 69 kW CX
527MHz 69 kW TBS
533MHz 69 kW TX
539MHz 69 kW EX
545MHz 69 kW NTV
551MHz 68 kW NHK(Edu.)
557MHz 68 kW NHK
10km
15km
20km
Tokyo
metropolitan
area
TOKYO
SKYTREE
Measurement
points
25 km
Distance (km)2 4 6 8 10 20
0
0.5
1
-40
-30
-20
-10
-50
Outp
ut
dc v
oltage (
V)
Inp
ut
pow
er
(dB
m)
Input power
Output voltage
L type LPF
Cockcroft-Walton
type rectifier(m=2)
Diode
HSMS-285C
Load resistance terminals
1.6kWAntenna
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Wireless-Powered ZigBee in Same Frequency Band
17
ON ONON
OFF OFF
ZigBee
Rectenna
Mic
row
ave P
ow
er
Zig
Be
e C
om
mu
nic
atio
n
Mic
row
ave P
ow
er
Zig
Be
e C
om
mu
nic
atio
n
Mic
row
ave P
ow
er
Zig
Be
e C
om
mu
nic
atio
n
Time
• We propose MPT-ZigBee system at
same frequency of MPT and ZigBee (at
2.45GHz) with scheduling algorism.
• We can increase a limit power without
any interference (5pW/cm2 (CW)
-> 1.91mW/cm2 (pulse, no scheduling)
- > 2.61mW/cm2 (pulse, scheduling)
Intermitted
(Pulse) MPTDevice Type
As join in network
As not join in network
End device 9.46 mW 61.8 mW
Ichihara, T, et al., “Study and Development of an Intermittent Microwave Power Transmission System for a ZigBee
Device”, Proc. of 2014 IEEE Wireless Power Transfer Conference (WPTc2014), 2014, pp.40-43
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Weak point of ubiquitous network
society is a power source.
We propose a wireless power source with
microwave power transmission (MPT). In
most advanced system, we bring only a
receiving system, rectenna instead of heavy
battery. At first step, we try to charge a
battery via microwave power.
Receiving
System
Transmitting System
Ubiquitous Power Source (UPS)
Wireless Power source
in every time
and in everywhere“Ubiquitous Power Source”
Wireless
Charge
Shinohara, N., et al., “Study on Ubiquitous Power Source with Microwave Power Transmission”, Proc. of
International Union of Radio Science (URSI) General Assembly 2005, C07.5(01145).pdf, 2005 18
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Demonstration of WPT-powered Sensors with Drone
19
自律プログラム飛行高度30m~50m
高度 約6m~8m
遭難者発見データ飛行経路情報マルチコプタ-動作情報WBLS動作情報
遭難者救援支援マルチコプタ基地
電波障害物
遭難者(救命カード保有)
中継器(必要に応じて)
電子基準点
遭難者救助対策本部
最大探査距離(TBD)km
マイクロ波電力
遭難者IDデータ
次期マルチコプター
by WiPoT, Kyoto Univ., Mini-Surveyor Consortium, Autonomous Control Systems Laboratory Ltd.
Demo (Jul. 16, 2015)
Applications : Rescue of victims, WPT-powered sensors at volcano,
Inspection of infrastructures (Bridges, Tunnels..)
Victim(with Rectenna-
Vital Sensor Card)Drone Station
for Rescue
Obstacle of Radio
ID Data of
Victim
Height 6-8m
Microwave powerVictim Data
Flight Path Data
Drone Health Data
WBLS Health Data
Transponder(If necessary)
Autonomous Programmed Flight
Height 30-50m
Next Term Drone
Electric Reference Point
Rescue HeadquarterFlying Drone
WPT-Powered
Sensor
4mMicrowave
(5.8GHz, -8.74W)
Maximum Search Distance (TBD) km
5.8GHz, 8.74W from 8x8 array (21dBi)
6.1mW Received at 2 rectennas (10.2dBi)
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Commercial Products of WPT via Radio Waves
• Venture Companies of Wireless Charger of Smart Phone* ‘Cota’ by Ossia inc. (WiFi-Band) http://www.ossiainc.com/
* ‘Wattup’ by Energous corp. (2.45GHz and 5.8GHz Band)
http://www.energous.com/
• Japanese Company (Dengyo)of Battery-less Sensor
(900MHz-Band) http://www.den-gyo.com/solution/solution10_b.html
UHF Band Transmitter
(920 MHz Band)
Re
ctifyin
gC
ircuit
Tran
s-M
itter
Sensor &Micro Computer
A few m
Wireless Power
DataTransmission315 MHz Band
Wireless Sensor
20
KDDI (Big 3 Carrier
in Japan) supports
Ossia
Based on FCC-15
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How Cota Works With Obstruction by Ossia
21
Unlike radio waves that pass through a human body, Ossia’s Cota technology considers our bodies to be obstructions and therefore power signals avoid them.
Obstructions Stay SafeIf an obstruction (humans, pets,
plants, etc.) is between the
receiver and the transmitter, the
reflections of the beacon signal
pulses (off of the walls/furniture)
will naturally find their way to the
transmitter.
Pulse PlaybackIn turn, the transmitter sends pulses that
mimic (playback) each incoming beacon
signal characteristics with opposite phase.
The outgoing pulses will have the exact
shape and take the same path of each
incoming beacon signal, using the same
reflections and creating a power signal that
is focused only on the receiver while
inherently avoiding obstructions.
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Silicon Valley’s Rumor (2016)• iPhone8 will install chip of Wireless Charging via Radio
Wave by Energous
“With an Energous transmitter in your office, your phone will constantly be charging even while it’s in your pocket as you sit at your desk and work.”
22
https://www.bloomberg.com/news/articles/2016-01-29/apple-said-developing-wireless-charged-phone-for-
as-soon-as-2017-ijz3i4si
http://www.phonearena.com/news/Upcoming-iPhone-8-could-feature-wireless-charging-unlike-anything-
weve-seen-yet_id87639
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23
MILAX Airplane Experiment(Japan, 1992)
With Kobe Univ., CRL, Nissan motor co., Fuji heavy industry co., ISAS in Japan
Transmitter(1.25kW)
Microwave(2.411GHz)
http://friendsofcrc.ca/SHARP/sharp.html
Electrical Beam Control with Phased Array Mechanical Beam Control
with Parabolic Antenna
Fuel-free Airplane MILAX
SHARP Experiment(Canada, 1987)
MPT to Flying Drone (Airplane)
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24
Future Dream of MPT:
Solar Power Satellite (SPS)
1GW Solar Power Station
2kmf Solar Cells
2kmf Microwave Antenna
< 10,000 ton weight
36,000km
Wireless Power
Transmission
via Microwave
2kmf
Receiving Antenna
Energy Availability Factor
Ground PV
: < 15% (Night, Rain…)
Space PV (SPS)
: >90% (No Night in 36,000km Orbit,
No Rain by Microwave Propagation)
-> SPS is huge, stable, and CO2-less
Power Station
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PowerSupply
-Control
PowerSupply-Main
AC
100V
AC
200V
(3φ
)
ReferenceSignal
RSCMaster Unit(R
EF O
UT)
DC
DC
BFN
HPA MDL
Sub-array
SUM
ERR
Radiator
TRK-RCV
DEM
CPUCARD
DIV
PowerSupplyCard
BFNC
BFN
D/C
Power Transmitting Module #1
RSCSlave Unit
Power Transmitting Panel
5.8GHz
SUM
Heat-Pipe
Feed
ANTFirst StageHPA MDL
BSC Section
BSC Section
Phase ControlSignal
RSC: Reference Signal Control BSC: Beam Steering Control BFN: Beam Forming Network BFNC: BFN for Control Signal
DIV: Divdier HPA MDL: High Power Amplifier
Module ANT: Antenna
: RF/IF Signal : Control Signal: Power Line : Thermal Path
BFN(Beam Forming Network)
HPA MDL (PAE >70%)
(High Power amplifier Module)
60cm x 60cm, ≧ 450W , ≦1.9kg
Sub-array Image
Power Transmitting Module Image
Transmitting ANT
(76 Sub-array ANT)
Sub-array ANT
______(4 elements)
Developed Thin Phased Array Antenna (FY2009-2014)by Japanese SPS Committee
(66mm x 66mm x 25mm(Thickness))
(120cm x
120cm) ,
5.8GHz,
1.8kWCW
Thin
Phased
Array
Developed by Mistubishi Electric Corp., Supported by METI 25
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Power Density~350W/ /㎡at rectenna center
~10W/ /㎡at rectenna edge
WPT Ground Test
Microwave
Beam
MPT Experiment on Feb. 2015Thin-High Efficiency Phased Array with GaN MMIC
55m
2.5cm thickness phased array
GaN MMIC Amplifiers
5.8GHz, 1.8kW
Developed by Mistubishi Electric Corp. (Phased Array), IHI Aerospace (Rectenna Array), Supported by METI 2
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27
Theory and technology of WPT via Radio Waves
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28
Efficiency of Wireless Power Transfer via Radio Waves
RF Power
(Wired)
Frequency
Converter
RF Generator
DC Power
DC Power
(1) DC-RF conversionRF Power (Wireless)
(3) RF-DC conversion(2) Radio Wave Propagation
- Beam Efficiency -
Total Efficiency of WPT
= (1) X (2) X (3)
World Record : 54% (Beam-type, Lab.)by W. C. Brown in 1975
Magnetron
+ Horn Antenna
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29
Rectenna – Rectifying Antenna –Radio Wave -> DC Power Converter
Brown&JPL Rectenna
(2.45GHz) 1970-75
Rectenna by Hokkaido Univ.
(2.45GHz) 1984
Rectenna byTexas A&M Univ.
(35GHz) 1992
Rectenna
byDENSO co.
(21GHz) 1997 Commercial Rectenna by DENGYO co. (2.45GHz) 2011
Rectenna
by Kyoto Univ.
(5.8GHz) 2001
Rectenna by Intel co.
(674 - 680 MHz) 2009
antenna
diode
antenna
diodeantenna
diode(backside)
antenna
diode
An-tenna
LPF
OutputFilterwith
Capa-citance
Radio Wave
DCTo Load
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Frequency Characteristics of Efficiency of Rectenna
30
2.45GHz 5.8GHz 14GHz 24GHz 35GHz
100%
50%
0%
10GHz
60%
70%
80%
90%
40%
30%
20%
10%
100GHz45GHz 62GHz 72GHz
Frequency
RF-
DC
Co
nve
rsio
n E
ffic
ien
cy
: Diode : CMOS
antenna
diode
by Brown&JPL
(2.45GHz) 1970-75
by Texas A&M Univ.
(35GHz) 1992
Products by DENGYO co. (2.45GHz) 2011
by DENSO co.
(14GHz) 2000
MMIC by Kyoto Univ.
(24GHz) 2012
by École Polytechnique
Montréal (94GHz) 2015
antenna
diode
by Tel-Aviv University
(75-110GHz) 2014
532um x 910um
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Input Poweror Connected Load
T.- W. Yoo and K. Chang, “Theoretical and Experimental Development of 10 and 35 GHz Rectennas”, IEEE Trans. MTT, Vol.40, No.6, 1992, pp.1259- 1266
Higher Order
Harmonics Effect
How do we increase the RF-DC conversion efficiency at energy harvesting?
31
RF-DC conversionefficiency
100%
V
I
VJ
(0.2-0.3V)
Vbr
(10-30V)
-VJ
Rdiode
“rectenna”region“detector”
region
VJ Effect
Vbr EffectDiode Maximum
Efficiency Curve
To increase the peak RF-DC conversion efficiency1) With low wRC diode2) High voltage at diode (almost breakdown)3) Higher harmonics combination (like class-F amplifier)
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How to increase efficiency of rectenna
• Choose theoretically 100% circuit
• Reduce number of diode which is loss factor
– Recommend single shunt rectifier
• Choose diode with Low wRC diode
• Design circuit with higher harmonics combination(like class-F amplifier)
• Suppress higher harmonics re-radiation
• Match impedance at input and output
• To add high voltage (almost breakdown)
• (Additionally) consider combination of antenna32
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Advanced Rectenna
• Wide Band
– Frequency
– Load
– Power -> especially low power
33Input Power
or Connected Load
Higher Order
Harmonics Effect
RF-DC conversionefficiency
100%
VJ Effect
Vbr EffectDiode Maximum
Efficiency Curve 800MHz
Example of Modulated Wave
(OFDM) for Harvesting
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Expansion of optimum input, load, frequency, etc.
34Ferran Bolos, et al. (CTTC), “A UHF Rectifier with One Octave Bandwidth
Based On a Non-Uniform Transmission Line”. Proc. of IMS2016
• Broadband Impedance Matching (CTTC, Spain, 2016)
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lg/4 line
Diode
Sector-type Class-F Load
Broadband F-class Load Rectenna by Kyoto Univ.
Normal Stubs
Sector Stubs
35
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Advanced Rectenna
• Wide Band
– Frequency
– Load
– Power -> especially low power
36Input Power
or Connected Load
Higher Order
Harmonics Effect
RF-DC conversionefficiency
100%
VJ Effect
Vbr EffectDiode Maximum
Efficiency Curve 800MHz
Example of Modulated Wave
(OFDM) for Harvesting
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Self-powered DCM Buck-boost Converter
37
Operating waveform
Expansion
Yong Huang, Naoki Shinohara, and Tomohiko Mitani, “A Constant Efficiency of Rectifying Circuit
in an Extremely Wide Load Range”, IEEE-Trans. MTT, Vol. 62, No.4, pp.986-993, 2014
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Experiment on Self-powered RF-DC-DC Circuit
38
RF-DC rectifier + Buck-boost converter experimental
results : Comparison of efficiency-load
System efficiency with converter
Rectifier without
converter
Rectifier with converter
Buck-boost converter
Yong Huang, Naoki Shinohara, and Tomohiko Mitani, “A Constant Efficiency of Rectifying Circuit
in an Extremely Wide Load Range”, IEEE-Trans. MTT, Vol. 62, No.4, pp.986-993, 2014
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Advanced Rectenna
• Wide Band
– Frequency
– Load
– Power -> especially low power
39Input Power
or Connected Load
Higher Order
Harmonics Effect
RF-DC conversionefficiency
100%
VJ Effect
Vbr EffectDiode Maximum
Efficiency Curve 800MHz
Example of Modulated Wave
(OFDM) for Harvesting
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Expansion of optimum input, load, frequency, etc.
40“Transmission Line Resistance Compression Networks
for Microwave Rectifiers” Taylor W. Barton et al., MIT, USA
• Active Impedance Matching (MIT, 2015)
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Selective Matching Circuit by Kagoshima Univ.
41
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Consideration of Diode
42An E-pHEMT Self-biased and Self-synchronous Class E Rectifier
M. N. Ruiz and J. A. García, University of Cantabria, Spain, 2015
• Zero Bias Diode -> Low Efficiency (Bad diode parameter?)
• Self-biased and Self-synchronous Rectifier (Univ. of Cantabria)
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Low Power Rectenna – How to add high voltage at diode
• Charge Pump -> High Voltage but Low Efficiency
• Output Filter Matching (Kyoto Univ. etc., Japan)
- 50% @ 1mW, 5.8GHz (2004)
• Standing Wave by Reflection
(Okayama Univ., Japan, 2004)
• Rectifying Circuit with Resonator
(Tohoku Univ. (2006), Toyama Univ. (2013), Japan)
- 40% @ 100mW, 900MHz
• High Impedance Circuit and Antenna(Kanazawa Inst. Tech. (2016), Japan)- 40% @ 100mW, 900MHz
43
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RISH, Kyoto Univ. 41
Introduction of Activities of WPT
in IEEE
44
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45
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IEEE Wireless Power Transfer Conference (WPTc)
1st IMWS-IWPT (2011)2nd IMWS-IWPT (2012)at Kyoto, Japan
1st WPTC (2013)at Perugia, Italy
2nd WPTC (2014)at Jeju, Korea 3rd WPTC (2015)
at Boulder, USA
46
4th WPTC (2016)at Aveiro, Portugal
5th WPTC (2017)at Taipei, Taiwan
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RISH, Kyoto Univ. 44
Conclusion
47
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SPS
Buildings
Vehicles
Smart Energy
Communications –Power Coexistence
Energy Security
Infrastructure of Communications –Power Coexistence
Power Storage
Ubiquitous Power Source
Saving Energy
Our Dream : Wireless Power Society
Ubiquitous Power Source in Emergency
48
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WPT Books
Wireless Power Transfer via Radiowaves (Wave Series)
Naoki ShinoharaISTE Publishing &
John Wiley & Sons, Inc., UK & USA2014.1
ISBN 978-1-84821-605-1(Paper Book and Kindle) 49
Wireless Power Transfer Algorithms, Technologies
and Applications in Ad Hoc Communication Networks
ed. Sotiris Nikoletseas, Yuanyuan Yang,
and Apostolos Georgiadis, Springer, 2016.7,
ISBN 978-3-319-46810-5
Online Journal of Wireless Power Transfer
Cambridge Press
http://journals.cambridge.org/action/displayJournal?jid=
wptCall for Paper!!