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Time Reversed Electromagnetic Wave
Propagation as a Novel Method of Wireless Power Transfer
Frank Cangialosi, Tyler Grover, Patrick Healey, Tim Furman, Andrew Simon, Steven M. Anlage
1
Current State of Long-Range WPT
Microwave Beaming
Ubiquitous WPT requires greater range than provided by near-field technologies
Current State of Long-Range WPT
Microwave Beaming
XObstructionsPrecise Alignment
Ubiquitous WPT requires greater range than provided by near-field technologies
Current State of Long-Range WPT
Microwave Beaming
ObstructionsPrecise Alignment
Ubiquitous WPT requires greater range than provided by near-field technologies
Current State of Long-Range WPT
Microwave Beaming
ObstructionsSafety HazardPrecise Alignment
Ubiquitous WPT requires greater range than provided by near-field technologies
-15-10-5 0 5
10 15
0 2 4 6 8 10 12 14
Vo
ltage (
mV
)
Time(µs)
Time Reversal
S
T
1. Time Forward StepTarget requests power, source records sona
Target Device
Power Source
A signal-focusing technique
(Enclosed cavity with reflecting walls)
-15-10-5 0 5
10 15
0 2 4 6 8 10 12 14
Vo
ltage (
mV
)
Time(µs)
Time Reversal
S
T
1. Time Forward Step
“Sona"
Gaussian Pulse
(50 ns)
Target requests power, source records sona
Target Device
Power Source
A signal-focusing technique
(Enclosed cavity with reflecting walls)
-15-10-5 0 5
10 15
0 2 4 6 8 10 12 14
Vo
ltage (
mV
)
Time(µs)
Time Reversal
S
T
2. Time Reverse Step
-400-300-200-100
0 100 200 300 400
13.45 13.46 13.47 13.48 13.49 13.5 13.51
Volta
ge (
mV
)
Time(µs)
“Sona"
1. Time Forward StepTarget requests power, source records sona
Source reverses and broadcasts, sona reconstructs on target
Power Source
Target Device
A signal-focusing technique
(Enclosed cavity with reflecting walls)
-15-10-5 0 5
10 15
0 2 4 6 8 10 12 14
Vo
ltage (
mV
)
Time Reversal
S
T
2. Time Reverse Step
-15
-10
-5
0
5
10
15
0 2 4 6 8 10 12 14
Voltage (mV)
Time(µs)
-400-300-200-100
0 100 200 300 400
13.45 13.46 13.47 13.48 13.49 13.5 13.51
Volta
ge (
mV
)
Time(µs)
“Sona"
1. Time Forward StepTarget requests power, source records sona
Source reverses and broadcasts, sona reconstructs on target
Power Source
Target Device
A signal-focusing technique
(Enclosed cavity with reflecting walls)
-15-10-5 0 5
10 15
0 2 4 6 8 10 12 14
Vo
ltage (
mV
)
Time Reversal
S
T
2. Time Reverse Step
-15
-10
-5
0
5
10
15
0 2 4 6 8 10 12 14
Voltage (mV)
Time(µs)
-400-300-200-100
0 100 200 300 400
13.45 13.46 13.47 13.48 13.49 13.5 13.51
Volta
ge (
mV
)
Time(µs)“Reconstruction” pulse
“Sona"
1. Time Forward StepTarget requests power, source records sona
Source reverses and broadcasts, sona reconstructs on target
Power Source
Target Device
A signal-focusing technique
(Enclosed cavity with reflecting walls)
-15-10-5 0 5
10 15
0 2 4 6 8 10 12 14
Vo
ltage (
mV
)
Time Reversal
S
T
2. Time Reverse Step
-15
-10
-5
0
5
10
15
0 2 4 6 8 10 12 14
Voltage (mV)
Time(µs)
-400-300-200-100
0 100 200 300 400
13.45 13.46 13.47 13.48 13.49 13.5 13.51
Volta
ge (
mV
)
Time(µs)“Reconstruction” pulse
“Sona"
1. Time Forward StepTarget requests power, source records sona
Source reverses and broadcasts, sona reconstructs on target
Power Source
Target Device
A signal-focusing technique
(Enclosed cavity with reflecting walls)
Good for rectification
5
Time Reversal for WPT
1
Ray-chaotic environment
Requires… Provides…
2 Reflective surfaces
3
Spatial reciprocity of the wave equation
2 Resilience to obstructions
1 Range (not limited to free space drop-off)
3 Power concentrated at any given location
6
Experimental Setup
+35
0 (mm)
-35
Scattering panels ensure ray chaos
OscilloscopeAWGPSG
Device (on MikroMove)
Power Source (5Ghz, 3dBm)
Wave Generation (TX) Wave Analysis (RX)
MATLAB
7
Spatial Profiling of Reconstruction
+35
0 mm
-35
Target: 0
Constant Velocity0.2 mm/s
7
Spatial Profiling of Reconstruction
+35
0 mm
-35
Target: 0
Constant Velocity0.2 mm/s
7
Spatial Profiling of Reconstruction
+35
0 mm
-35
Target: 0
Constant Velocity0.2 mm/s
7
Spatial Profiling of Reconstruction
+35
0 mm
-35
Target: 0
Constant Velocity0.2 mm/s
8
Spatial Profiling of Reconstruction
V (x) = a ·����sinc
✓x+ c
b
◆����+ d
x
V (x)
8
Spatial Profiling of Reconstruction
V (x) = a ·����sinc
✓x+ c
b
◆����+ d
x
V (x)
8
Spatial Profiling of Reconstruction
Background noise
V (x) = a ·����sinc
✓x+ c
b
◆����+ d
x
V (x)
8
Spatial Profiling of Reconstruction
Background noise
V (x) = a ·����sinc
✓x+ c
b
◆����+ d
x
V (x)
9
Targeting a Moving Receiver
0
0.5
1
1.5
2
2.5
3
3.5
0 20 40 60 80 100 120 140
Peak-
To-P
eak
Volta
ge (
V)
Time (s)
V(t)
“Refresh” the sona before it gets stale
9
Targeting a Moving Receiver
0
0.5
1
1.5
2
2.5
3
3.5
0 20 40 60 80 100 120 140
Peak-
To-P
eak
Volta
ge (
V)
Time (s)
V(t)
“Refresh” the sona before it gets stale
9
Targeting a Moving Receiver
0
0.5
1
1.5
2
2.5
3
3.5
0 20 40 60 80 100 120 140
Peak-
To-P
eak
Volta
ge (
V)
Time (s)
V(t)
“Refresh” the sona before it gets stale
9
Targeting a Moving Receiver
0
0.5
1
1.5
2
2.5
3
3.5
0 20 40 60 80 100 120 140
Peak-
To-P
eak
Volta
ge (
V)
Time (s)
V(t)
“Refresh” the sona before it gets stale
9
Targeting a Moving Receiver
0
0.5
1
1.5
2
2.5
3
3.5
0 20 40 60 80 100 120 140
Peak-
To-P
eak
Volta
ge (
V)
Time (s)
V(t)
“Refresh” the sona before it gets stale
“Dead” time
9
Targeting a Moving Receiver
0
0.5
1
1.5
2
2.5
3
3.5
0 20 40 60 80 100 120 140
Peak-
To-P
eak
Volta
ge (
V)
Time (s)
V(t)
“Refresh” the sona before it gets stale
“Dead” time
10
Targeting a Moving Receiver
0
0.5
1
1.5
2
2.5
3
3.5
0 20 40 60 80 100 120 140
Peak-
To-P
eak
Volta
ge (
V)
Time (s)
V(t)
“Refresh” the sona before it gets stale
0
0.5
1
1.5
2
2.5
3
3.5
0 20 40 60 80 100 120 140
Peak-
To-P
eak
Volta
ge (
V)
Time (s)
V(t)
Experimental Results
Potential WPT System
Supplier searches for participating devices (which may or may not have charge)
Steady State
Initialization
Small fraction of power reflected by device, allowing supplier to find new location
Talk Session 5 Friday,17:45
(Selective Collapse of Nonlinear Time Reversed Electromagnetic Waves)
12
Limitations And Future Work
Transfer efficiencyUse multiple channels
Environmental lossesInvestigate and mitigate
Dead timeUse dedicated hardware TX and calculate new sona simultaneously
These limitations are dependent on our lab equipment, they are not fundamental limitations of the technique
13
Summary
TimeReversal
is a promising new basis for long-range WPTcan transmit energy to receivers in motiondoes not require the receiver to be powered
Talk Session 5 Friday,17:45
(Selective Collapse of Nonlinear Time Reversed Electromagnetic Waves)
Poster Session 2 Friday,14:40
(Time Reversed Wave Propagation as a Novel Method of WPT)
[email protected]@umd.edu