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?