Wireless Power
Applications in Bridge Monitoring
Presented by RF On
October 11, 2007
Project Overview
Demonstrate the feasibility of wireless
power transmission through the example
of wireless bridge monitoring sensors.
• Wireless power collection
• Characterization of low power
transceivers (TNC’s)
• Develop at least two sensor types
• Separate antennas for power and
communication
• Bi-directional serial communication
between sensor and base station
• Communication through 1” of
concrete
System Block Diagram
Sensor Main board
Sensors: Temperature
& Humidity
Sensors:
Accelerometer
Parts List
Maker
Micro Processor
TNC’s
Texas Instruments
TI, Nordic
Temp./Humidity Sensor Sensiron
Accelerometer
Analog Devices
Antenna Substrate
PCB- 3 Revs
Printing/Binding
Misc. Parts
Total
Advanced Circuits
Kinko’s
Budget
$40.00
$200.00
$200.00
$140.00
$200.00
$800.00
$100.00
$250.00
Money Spent
Sample
$75.00
$90.00
$25.00
Donation
$110.00
$300.00
$2030.00 $600.00
Dipole Simulation
S11
S11
0
40
Phase [deg]
Mag. [dB]
20
-5
-10
0
-20
-40
-60
-15
0
2
4
6
Frequency
8
10
0
2
4
6
8
10
Frequency
S11
•Simulation of the Antenna (design
frequency 2.4GHz) in Momentum
(Advanced Design System - Agilent) we
can produce plots of reflection and phase.
•By adjusting the width of the antenna we
can produce the specified impedance. The
impedance is dictated by the diode
selected for the rectification stage
(discussed later).
m1
freq (1.000GHz to 10.00GHz)
m1
freq=2.459GHz
d2_4G_3_mom_a..S(1,1)=0.216 / 8.707
impedance = Z0 * (1.537 + j0.105)
Antenna Fabrication
•Simulated antennas were fabricated. (Frequency 2.4GHz)
•In order to compare the dipole antennas to the patch antenna, an
array of dipoles were constructed on a substrate with the same
area as the patch.
•Within the given area, different densities of the dipole antennas
were constructed and tested.
Antenna Testing Procedure
• Calibrate measurement system to find
defined RF incident power density (MATLAB
Automated).
•Power density calculation included in
documentation
PC
(MATLAB and
GPIB Control)
RF
Source
Power Meter
Hewlett Packard, 437B
Power Meter.
Hewlett Packard, 83650A 10MHz –
50GHz, 8360 Series Synthesizer
Sweeper.
Power
Amplifier
Calibrated
Horn Antenna
Calibrated
Horn Antenna
Hewlett Packard,
83020A Power Amplifier
AEL, American Electronic
Laboratories, inc 2-18GHz, Model # H1498
AEL, American Electronic
Laboratories, inc 2-18GHz, Model #
H-1498
Antenna Testing Procedure
•Place antenna in chamber and connect to programmable load
(MATLAB Automated).
•Take measurements at each power density (Rectified DC Power
vs. Load Resistance)
PC
(MATLAB)
RF Source
DC Test source
(DC load emulation)
Hewlett Packard, 83650A 10MHz –
50GHz, 8360 Series Synthesizer
Sweeper.
Agilent Technologies N3280A 10V, 0.5A,
Component Test DC source.
Power
Amplifier
Calibrated
Horn Antenna
Hewlett Packard, 83020A
Power Amplifier
AEL, American Electronic Laboratories, inc 218GHz, Model # H-1498
Rectenna
Patch Rectenna 2.4GHz
Results of the patch antenna at 2.4 [GHz] with linearly polarized
RF power.
(Units of incident RF power density are in [uW/cm2])
Dipole 2.4GHz
•Results of the dipole antenna at 2.4 [GHz] with linearly polarized
RF power.
(Units of incident RF power density are in [uW/cm2])
•The output power of the dipole is about 1/8 of the power output of
the patch at the same incident power densities. (Both are matched
for 2.45 GHz)
Dipole array 2.4GHz
Dipole array 60X60mm
Patch antenna 60X60mm
An array of dipoles with same effective area as the patch antenna
produces 2.6 times more power for the same incident wave!
Software Block Diagram
Inputs and Outputs
Display
Inputs
Sensor
•Sensor Data
Outputs
•Sensor Data
•Sensor Type
•Sensor Type
•On/Off or
Start/Stop
•On/Off or
Start/Stop
Base Station software
Inputs
•Sensor Type
Outputs
•Sensor Data
•On/Off or
Start/Stop
•Sensor
Connection
Sensor Software
Inputs
•Sensor Data
Outputs
•Sensor Type
•On/Off or
Start/Stop
Display software
Software Functions- Base
• Wait for relay signals from display station
– Checking USB/Serial adapter
– Upon receipt relay signals to sensor
• Wait for response from sensor
– Poll status register of transceiver for sensor
data, and stop signal from display
– Upon receipt of stop signal relay to sensor
– Upon receipt of sensor data relay to Display
• Repeat
Software Functions- Sensor
• Wait for signals from base
– All sensors turned off until receipt of start
signal
– Upon receipt power up sensor and beginning
polling until stop signal is received
– Do any analog to digital conversion from the
sensors
• Transmit sensor data to base
– While polling send data to base immediately to
save storage
• Turn off sensor and repeat.
Software Functions- Display
• Transmit signals to Base station upon
request from user
• Translate raw sensor data
• Output in graphical interface
• Store data with option of exporting
Software Development/Testing
MSP430F1232
NRF24L01
• Range test
– Simple communication program that
echoes data back and forth between two
units
– Check range of the different transceiver
options
Task Assignments
Nathan
– Software development
Erez
– Optimization of DC/DC conversion circuitry
– Rectenna optimal load characterization
– Decreasing rectenna polarization dependency
Sarah
– Documentation & Scheduling
– Research of Thin Film Batteries/Sensors/Concrete
Packaging
Anthony
– Base station design
– Hardware Testing
Hardware Schedule
Software & Testing Schedule
Milestone I Deliverables
• Rev. 1 base station designed,
assembled, and operational
• Rev. 1 sensor boards designed,
assembled, and testing completed
• Sensor ‘packaging’ research
completed
• Software testing on functional boards
completed
• First draft of Technical User’s Manual
complete
Milestone II Deliverables
• Final base station design assembled, and
testing completed
• Final sensor boards designed, assembled,
and testing completed
• Decision for inclusion of additional
sensors (associated hardware completed if
included)
• Sensor packaging designed and
assembled
• Optimized DC/DC conversion circuitry
• GUI designed and tested
• Update of Technical User’s Manual and
User’s Manual
Expo Deliverables
• Functional circuit embedded in
concrete - testing completed and
characterized
• Software optimized
• Final Technical User’s Manual and
User’s Manual
Credits
Thank you to Prof. Zoya Popovic and
Prof. Regan Zane for their assistance
with:
•
•
•
•
Time
Knowledge
Lab equipment and facilities
Monetary support
Questions?