1. Investigation of Wireless Power Transfer in Through-wall Applications
July 5, 2012
By: Matt Hoang
Supervising Professor: Dr. J.C. Chiao

2. Objectives
To characterize efficiencies and power transfer of inductively coupled antenna through different media
Hypothesis – minor attenuation due to power absorption in dielectric material
Application – Develop wirelessly powered lighting system
UTA REU: Sensors and Applications
11/8/2018

3. Test Setup AC Voltage source Square Wave at 1.3MHz DC Source at 6V
Class-E Amplifier
Transmitter
Series LC
Transmitter Coil
Receiver
Parallel RLC
500 Ohm Load
Receiver Coil
UTA REU: Sensors and Applications
11/8/2018

4. Test Procedure
Tune Capacitance at Transmitter for Air at 4.5-cm and 8.5-cm
Insert Material between the coils (wood, concrete, water)
Measure the change in voltage and current
Retune Capacitance to peak voltage
Vary frequency to attempt to return to same voltage as in air
UTA REU: Sensors and Applications
11/8/2018

5. Results
UTA REU: Sensors and Applications
11/8/2018

6. Results Output, W Brick Wood Drywall Spacing, cm 4.4 8.5 Tuned (Air)
5cm Coil Set
Output, W
Brick
Wood
Drywall
Spacing, cm
4.4
8.5
Tuned (Air)
0.449
0.165
0.392
0.163
0.406
0.157
Untuned (Medium)
0.424
0.388
0.155
0.399
0.154
Tuned (C1)
0.428
0.161
Tuned (Freq.)
0.162
Tuned (C2)
UTA REU: Sensors and Applications
11/8/2018

7. Through-Wall Experiment
15-cm with 10 Turns Transmitter/Receiver Coils
Total wall thickness: 31cm
Achieved Total Output Power of 25mW at 2% Efficiency
Success in Returning to Same Voltage as Air in same Distance
UTA REU: Sensors and Applications
11/8/2018

8. Spiral Antennas
Yielded vastly different results from the radial antennas
Observed 30-40% drop in power after tuning
However, tested with bigger spiral antennas (21.7 cm) and achieved similar results from radial experiment
UTA REU: Sensors and Applications
11/8/2018

9. Conclusion and Future Work
Hypothesis only correct for certain case (not general)
Have concluded that power loss in wireless power transfer depends on antenna type.
Radial antenna have minor loss however, have lower power output
Spiral has high power output but extremely sensitive to change in dielectric medium
Required to develop more tests for spiral antenna to further verify the data collected
Research Paper Submitted to APMC (Asian Pacific Microwave Conference) Titled: “Investigation of Wireless Power Transfer in Through-wall Applications”
UTA REU: Sensors and Applications
11/8/2018