N142-111 TITLE: Wide-Angle Acoustic Beam Steering with Arrays of PiezoCrystal Tonpilz Transducers

TECHNOLOGY AREAS: Materials/Processes, Sensors, Weapons

ACQUISITION PROGRAM: FNC ATT for Surface Ship Defense Against Complex Salvo & Full Sector Defense

RESTRICTION ON PERFORMANCE BY FOREIGN NATIONALS: This topic is "ITAR Restricted". The information and materials provided pursuant to or resulting from this topic are restricted under the International Traffic in Arms Regulations (ITAR), 22 CFR Parts 120-130, which control the export of defense-related material and services, including the export of sensitive technical data. Foreign nationals may perform work under an award resulting from this topic only if they hold the "Permanent Resident Card", or are designated as "Protected Individuals" as defined by 8 U.S.C. 1324b(a)(3). If a proposal for this topic contains participation by a foreign national who is not in one of the above two categories, the proposal may be rejected.

OBJECTIVE: Design, build, and test an array of piezocrystal Tonpilz SONAR transducers that can be steered over large angles with high directivity and low sidelobe levels.

DESCRIPTION: The Tonpilz design for SONAR transducers is widely used in large arrays in acoustic systems for undersea threat detection, weapons guidance, communication and the like. Exploiting single crystal piezoelectrics in Tonpilz transducers has led to single transducer elements with enhanced bandwidth, sensitivity, and source level in a smaller, lighter package when compared with legacy piezoceramic elements. [Ref 1 & 2] This topic addresses the next step, namely, building these single elements into large arrays with good array directivity and low sidelobes when steered over large angles, both in transmission and reception. Critical issues to be addressed include: element uniformity in large scale production, an array mounting structure that prevents element-to-element crosstalk, and minimizing coupling of elements mediated through the medium itself (seawater). [Ref 3 & 4]

PHASE I: Analyze what is required for a full array of piezocrystal Tonpilz transducers to have high directivity with low sidelobes both on transmission and reception. Devise a cost-effective means to meet these requirements and demonstrate the validity of the analysis and candidate solution with a small sub array. Targeting the analysis and solution at a specific SONAR array system would be a big plus.

PHASE II: Identify a candidate SONAR array and design, build, and test a full array of single crystal piezoelectric Tonpilz transducers that can be steered to large angles with low sidelobe levels.

PHASE III: Insert the piezocrystal array technology into a spectrum of Navy SONAR systems for threat detection, weapons guidance, communication and the like.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: In parallel to most Navy SONAR systems there are analogues in civilian commercial SONAR where undersea acoustic arrays are used for sea floor exploration, navigation, communication, and the like. Indeed, the commercial opportunities may initially be more fast-moving and lucrative than the present Fleet insertion opportunities.

REFERENCES:
1. J. M. Powers, M. B. Moffett, and F. Nussbaum, "Single crystal Naval Transducer Development" in Proceedings of the 2000 12th IEEE International Symposium on Applications of Ferroelectrics, vol. 1, pp. 351-354,2000.

2. Mark B. Moffett, Harold C. Robinson, James M. Powers, and P. David Baird, "Single-Crystal Lead Magnesium Niobate-Lead Titanate (PMN/PT) as a Broadband High Power Transduction material" Journal of the Acoustical Society of America, vol. 121, p. 2591, 2007.

3. Charles H. Sherman and John L. Butler, "Transducers and Arrays for Underwater Sound," Springer, 2007.

4. William S. Burdic, "Underwater Acoustic System Analysis" Prentice-Hall, 1984.

KEYWORDS: SONAR array; wide-angle beam steering; Tonpilz transducer; low array sidelobe levels; high array directivity; transducer array crosstalk; acoustic beamforming; single crystal piezoelectrics; PMN-PT; PIN-PMN-PT

** TOPIC AUTHOR (TPOC) **

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