Electrical optimization of power delivery through thick steel barriers using piezoelectric transducers

In many commercial, industrial, and military applications, supplying power to electronics through a thick metallic barrier without compromising its structural integrity would provide tremendous advantages over many existing barrier-penetrating techniques. The Faraday shielding presented by thick metallic barriers prevents the use of electromagnetic power-transmission techniques. This work describes the electrical optimization of continuouswave power delivery through thick steel barriers using ultrasound. Ultrasonic channels are formed by attaching pairs of coaxially-aligned piezoelectric transducers to opposite sides of thick steel blocks. The thickness of the steel considered is on the order of, or greater than, one quarter wavelength of the acoustic power signal inside of steel, requiring the use of wave propagation theory to properly analyze the system. A characterization and optimization methodology is presented which measures the linear two-port electrical scattering parameters of the transducersteel- transducer channel. Using these measurements, the simultaneous conjugate impedance-matching conditions at both transducers are calculated, and electrical matching-networks are designed to optimize the power transfer from a 50Ω power amplifier on one side of the steel block to a 50Ω load on the opposite side. In addition, the impacts of, and interactions between, transducer and steel geometries are discussed, and some general guidelines for selecting their relationships are presented. Measurements of optimized systems using transducers designed to resonate at 1 MHz with diameters from 12.7 mm to 66.7 mm, and steel block thicknesses from 9.5 mm to 63.5 mm, reveal power transfer efficiencies as high as 55%, and linear delivery of 81 watts through an optimized channel.

[1]  D. Pozar.  Microwave Engineering , 1990 .

[2]  D. A. Frickey.  Conversions between S, Z, Y, H, ABCD, and T parameters which are valid for complex source and load impedances , 1994 .

[3]  S. Mahlknecht,et al.  Low cost data transmission via metallic solids for sensor networking , 2005, Proceedings of the IEEE Symposium on Emerging Technologies, 2005..

[4]  Stewart Sherrit,et al.  Studies of acoustic-electric feed-throughs for power transmission through structures , 2006, SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring.

[5]  G.J. Saulnier,et al.  P1G-4 Through-Wall Communication of Low-Rate Digital Data Using Ultrasound , 2006, 2006 IEEE Ultrasonics Symposium.

[6]  Moshe Kam,et al.  Echo-Cancellation for Ultrasonic Data Transmission through a Metal Channel , 2007, 2007 41st Annual Conference on Information Sciences and Systems.

[7]  G.J. Saulnier,et al.  P3F-5 An Ultrasonic Through-Wall Communication System with Power Harvesting , 2007, 2007 IEEE Ultrasonics Symposium Proceedings.

[8]  Stewart Sherrit,et al.  Wireless piezoelectric acoustic-electric power feedthru , 2007, SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring.

[9]  T. Otterpohl,et al.  Remote acoustic powering and data transmission for sensors inside of conductive envelopes , 2008, 2008 IEEE Sensors.

[10]  Stewart Sherrit,et al.  High-power piezoelectric acoustic-electric power feedthru for metal walls , 2008, SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring.

[11]  Jussi Rahola,et al.  Power Waves and Conjugate Matching , 2008, IEEE Transactions on Circuits and Systems II: Express Briefs.

[12]  Moshe Kam,et al.  High bit rate ultrasonic communication through metal channels , 2009, 2009 43rd Annual Conference on Information Sciences and Systems.

[13]  Gary J. Saulnier,et al.  Finite Element Modeling and Simulation of a Two-Transducer Through-Wall Ultrasonic Communication System , 2009 .

[14]  Jeffrey A. Neasham,et al.  High bit rate communication through metallic structures using electromagnetic acoustic transducers , 2009, OCEANS 2009-EUROPE.

[15]  Xuedong Chen,et al.  Wireless energy transmission through a sealed wall using the acoustic-electric interaction of piezoelectric ceramics , 2009, International Conference on Smart Materials and Nanotechnology in Engineering.