Sensors Expo 2011
RF Energy Harvesting:
Th
Theory to Deployment
t D l
t
Harry Ostaffe
VP, Marketing & Business Development
Powercast Corporation
www.powercastco.com
©2011 Powercast Corporation
1
RF Energy is Everywhere
Billi
Billions of transmitters globally
ft
itt
l b ll
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©2011 Powercast Corporation
2
Perspective: Communication vs. Power
Power R
Requirem
ment
RF Sensitivity of Wireless Devices mA
Communication
Wake‐up Receiver
uA
Power Harvesting
0 ‐ nA
‐100
‐75
‐50
‐25
0
Input Power (dBm)
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©2011 Powercast Corporation
3
RF Power Sources
?
Intentional
Anticipated
Unknown
Ambient
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©2011 Powercast Corporation
4
Theory: Calculating Power Transfer
Power Determined by Friis Equation
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©2011 Powercast Corporation
5
Theory: Calculating Power Transfer
Simplified Friis Equation
Wavelength
Rx Power
Multiple parameters Multiple
parameters
determine received power
Rx Antenna Gain
Rx Antenna Gain
Tx Antenna Gain
Distance
Tx Power
Wireless Power Calculator
htt //
http://www.powercastco.com/wireless‐power‐calculator.xls
t
/ i l
l l t l
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©2011 Powercast Corporation
6
Theory: Simplistic Circuit Model
S11
RF Input
DC Output
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©2011 Powercast Corporation
7
Key RF Harvesting Characteristics
 Peak Efficiency
 Efficiency Range
 Frequency Range
 Sensitivity
 Output Voltage
Application scalability increased by having
wide performance range for all parameters.
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©2011 Powercast Corporation
8
What makes a harvester efficient?
 Proper RF Matching
o Harvester is non-linear
 Proper loading (DC matching)
o Generally requires a specific discrete or
emulated resistance
 Correct frequency
Efficiency declines rapidly
when conditions not met.
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©2011 Powercast Corporation
9
RF Matching Techniques
Rectenna (Rectifying Antenna)
 No matching network,
network No matching loss
(assuming lossless antenna dielectric)
 Difficult to measure diode complex impedance
 Requires specialized antenna design for each
application…does not scale across applications
Standard Impedance
 Matched to 50,, Negligible
g g
matching
g loss
 No special RF equipment required
 Works with standard antenna designs
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©2011 Powercast Corporation
10
Loading (DC Matching) Techniques
Maximum Power Point Tracking (MPPT)




Used
U
d with
ith other
th harvesting
h
ti technologies
t h l i
Requires monitoring of the DC operating point
Requires a voltage converter
Uses power (active)
Automatic Load Matching
 Automatically adjusts to AC and DC operating point
((Powercast technology
gy accomplishes
p
this in the RF domain))
 No voltage converter required for harvesting
 Uses no power (passive)
www.powercastco.com
©2011 Powercast Corporation
11
Powerharvester® Receivers
 Convert RF input to DC current
 Provide power management
P1110
 Frequency range: 850-950MHz
 RSSI and Data output
 Designed for standard 50Ω antennas
P1110
Continuous Power Output
• RF range:
a ge -5.0dBm
5 0d
to 20dBm
0d
• Output voltage: 1.8V to 4.2V
(configurable)
• Range of at least 3 meters
P2110
P2110
Pulsed Power Output
• RF range: -11.5dBm
11.5dBm to 15dBm
• Output voltage: 1.8V to 5.25V
(configurable and regulated)
• Range of at least 10 meters
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©2011 Powercast Corporation
12
Powerharvester® Efficiency Maintained Over
Wide Range of Input Power
RFF‐to‐DC Con
nversion Effficiency (%
%)
80
70
60
P1110 ‐ 915MHz, 3V
P2110 ‐ 915MHz, 1.05V
Power
50
40
30
20
10
Distance
0
‐12 ‐10 ‐8
‐6
‐4
‐2
0
2
4
6
8
10
12
14
16
18
20
Input Power (dBm)
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©2011 Powercast Corporation
13
Bandwidth Increases with Received Power
P2110 Harvester Efficiency
-3dBm ((500uW)) Input,
p
1V Load
Normalizzed Efficien
ncy
12
1.2
1
0.8
±20% over 850MHz
0.6
0.4
02
0.2
0
500
700
900
1100
1300
1500
1700
Frequency (MHz)
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©2011 Powercast Corporation
14
Ambient Wi-Fi Power
uW
400
Available Power Before Conversion (Estimated)
350
300
50mW
250
200
0 dBi
150
6 dBi
6 dBi
~4uW
100
Receiver Antenna
50
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Distance (meters)
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©2011 Powercast Corporation
4.0
4.5
5.0
15
Intentional Transmitter Power
uW
180
Available Power Before Conversion (Estimated)
160
140
120
100
3W EIRP Transmitter
915MHz
80
60
6 dBi
Receiver Antenna
Smaller antenna
40
20
0
0
5
10
15
20
25
30
Distance (meters)
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©2011 Powercast Corporation
16
Intentional Transmitter Coverage
Coverage Area – 3W transmitter (TX91501)
@ 60 feet ≈ 1900 ft2
@ 80 f
@ 80 feet ≈
3300 ft2
Average ≈ 2500 ft2
60 ft
80 ft
Effective range ff
increases with improved RF sensitivity of y
the receiver
Cost per ft
Cost
per ft2 ≈ $0.10 to $0.15
$0 10 to $0 15
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©2011 Powercast Corporation
17
Wireless Power Distribution is Similar to Cellular Model
 Distributed / Lower Power
 Any to Any Coverage
 Inherent Redundancy
I h
tR d d
 Enables Mobilityy
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©2011 Powercast Corporation
18
Ave
erage Po
ower Consumptiion
Practical Devices for RF Charging
Target Profiles for
RF‐based Wireless Power
Low‐power
Wireless
Sensors
Hours
Days
Weeks
Months
Years
Battery Run Time
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©2011 Powercast Corporation
19
RF-Powered Wireless Sensor System
Powercaster® Transmitter
915 MHz
915 MHz
One‐to‐Many Power Source
RF‐Powered Wireless Sensors
2.4 GHz
Temperature
Humidity
(WSN‐1001)
TX91501
Building Automation System Gateway
l
Li h
Light
BAS
Ethernet or Serial
WSG‐101
Diff. Pressure
Wireless Access Point
(for up to 100 devices)
(for up to 100 devices)
Battery‐less Sensors
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©2011 Powercast Corporation
20
System Deployment Example
Above ceilings
S
Inside Inside
rooms
BAS
Network
AP
Data
2.4 GHz
AP
Data range ~120ft indoors
Power
BAS Gateway
( SG 101)
(WSG‐101)
915 MHz
915 MHz
Behind walls
Power transmitter
(TX91501)
Powercast Wireless Sensor
Powercast Wireless Sensor
Temperature / Humidity / Light / Pressure / etc.
www.powercastco.com
©2011 Powercast Corporation
21
15 240 465 690 915 1,140 1,365 1,590 1,815 2,040 2,265 2,490 2,715 2,940 3,165 3,390 3,615 3,840 4,065 4,290 4,515 4,740 4,965 5,190 5,415 5,640 5,865 6,090 6,315 6,540 6,765 6,990 7,215 7,440 7,665 7,890 8,115 8,340 8,565 8,790 9,015 9,240 9,465 9,690 9,915 10,140 10,365 10,590 10,815 11,040 11,265 11,490 11,715 11,940 12,165 12,390 12,615 12,840 13,065 13,290 13,515 13,740 13,965 14,190 14,415 14,640 14,865 15,090 15,315 15,540 15,765 15,990 16,215 16,440 16,665 16,890 17,115 17,340 17,565 17,790 18,015 18,240 0.8
0.7
10
15 240 465 690 915 1,140 1,365 1,590 1,815 2,040 2,265 2,490 2,715 2,940 3,165 3,390 3,615 3,840 4,065 4,290 4,515 4,740 4,965 5,190 5,415 5,640 5,865 6,090 6,315 6,540 6,765 6,990 7,215 7,440 7,665 7,890 8,115 8,340 8,565 8,790 9,015 9,240 9,465 9,690 9,915 10,140 10,365 10,590 10,815 11,040 11,265 11,490 11,715 11,940 12,165 12,390 12,615 12,840 13,065 13,290 13,515 13,740 13,965 14,190 14,415 14,640 14,865 15,090 15,315 15,540 15,765 15,990 16,215 16,440 16,665 16,890 17,115 17,340 17,565 17,790 18,015 18,240 Deployment: Data Center Trial
Received Power (mW)
0.6
0.5
0.4
Node 4
Node 4
0.3
Node 5
0.2
Node 6
0.1
Node 7
0
12
Data samples: 15 minute intervals over 13 days
P k
Packets per Minute
Mi
8
6
Node 4
4
Node 5
Node 5
Node 6
2
Node 7
0
©2011 Powercast Corporation
www.powercastco.com
22
Future: Smartphone “Power App”
Battery‐less PAN device
IR
RF (ISM band)
(
)
Power Solution:
• Universal
• Mobile
• On‐demand
Smartphone
Phone‐based
Remote Control
Phone‐based
Wireless Power
Demo at http://www.youtube.com/powercastco
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©2011 Powercast Corporation
23
Summary
• RF energy harvesting / wireless power is a
practical
ti l and
d deployable
d l
bl solution.
l ti
• Most of today’s applications require
dedicated power transmitters
• Power network increases range
g and
improves performance
• RF harvesting technology is tracking with
ability to store the energy
www.powercastco.com
©2011 Powercast Corporation
24
Questions
Thank You!
Harry Ostaffe
+1
1 412-923-4774
412 923 4774
harry.ostaffe@powercastco.com
Emerging
Technology
P2100
Powerharvester®
TX91501
Powercaster®
www.powercastco.com
©2011 Powercast Corporation
P2110
Powerharvester®
P2110
Powerharvester®
25