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Cymbal transducers are typically grouped and arranged in planar arrays. For projector arrays, a wide bandwidth on the transmitting voltage response (TVR) spectrum is required for better underwater communication and data transmission within a short time. The purpose of this study is to develop a wideband cymbal array by controlling the center-to-center (CTC) spacing between the cymbal transducers in the array. In the practical design of the array, due to the arrangement of elements in one layer, the minimum CTC spacing between the cymbals is constrained to the diameter of the cymbals in use. To overcome this limitation, we propose a new dual-layer array structure. Finite element analysis of the cymbal array showed that the bandwidth was generally inversely proportional to the CTC spacing. We explained the mechanism of this relationship using a theoretical analysis of the mutual radiation impedance between the cymbals in the array. Subsequently, we identified the optimum CTC spacing to achieve the widest possible bandwidth for the cymbal array. The validity of the wideband array design was verified through the fabrication and characterization of prototype arrays. We confirmed that the two-layered arrangement could significantly widen the bandwidth of the cymbal array while maintaining the TVR above a specified level. [ABSTRACT FROM AUTHOR]

We report on the importance of considering manufacturing inaccuracies in underwater acoustic projectors by elucidating how small variations affect the response characteristics of a projector array in the presence of mutual-loading effects. A wave-based distributed mechanical model accurately calculates the changes arising from small variations, so rapid changes occurring in the vicinity of the transducer resonance can be simulated. The results showed the effects of mutual loading between projector units and confirmed that the changes can be drastically intensified in the presence of manufacturing inaccuracies. A voltage adjustment method to compensate for these changes is also demonstrated as a solution. This framework could guide the design of projector arrays in sound navigation and ranging (SONAR) systems for a variety of applications and, in particular, may contribute significantly to determining manufacturing tolerances. [ABSTRACT FROM AUTHOR]

• We developed a new equivalent circuit method (ECM) to analyze a conformal array. • This is the first work to analyze a conformal array of multimode Tonpilz transducers. • The new ECM can analyze the mutual interference between elements of the array. • The validity of the new ECM is verified by comparing results with experimental data. • The new ECM is faster than FEM by about 390 times in analyzing a conformal array. Commonly used underwater acoustic array types include planar and conformal arrays. The conformal array is favorable in practical active sonar systems as it offers superior acoustic performance, but its relatively complicated structure requires sophisticated analysis and design. In general, the characteristics of the array are analyzed using the finite element method (FEM). However, for complicated structures like the conformal array, the FEM is extremely time consuming and computation intensive. In this work, we developed a new equivalent circuit method (ECM) that can facilitate the analysis of the acoustical performance of a conformal array. The proposed ECM can include the effect of mutual interference between constitutive elements of the conformal array in addition to its own property of the array, which has not been possible with conventional equivalent circuits. The new ECM was applied to the analysis of the transmitting characteristics of a conformal array of multimode Tonpilz transducers. The Tonpilz transducer operated at both longitudinal- and flexural-mode resonances simultaneously to achieve a wide bandwidth. A new equivalent circuit to represent the multimodal properties of the Tonpilz transducer itself was derived as well. The validity and efficiency of the analysis of the Tonpilz transducer and the conformal array was verified by comparing the transmitting voltage response spectrum obtained by the ECM with those obtained by the FEM and experimental measurement. For the experimental validation, prototypes of the multimode Tonpilz transducers and their conformal array were fabricated and characterized. [ABSTRACT FROM AUTHOR]

• A new method to efficiently design an underwater array transducer has been developed. • The method is a new equivalent circuit coupled with an impedance network matrix. • The new method can consider both resonance and mutual interference of array elements. • The proposed method is significantly faster than conventional finite element method. • An underwater planar array is designed with the method to acquire a wider bandwidth. Underwater acoustic transducers are used to detect and track targets by using sound waves in underwater environments. To enhance the performance, they can be arranged in various formations to create arrays. However, acoustic interaction between the constituent channels of array transducers is inevitable, and it distorts their characteristics. In this study, the transmitting voltage response (TVR) spectrum of an acoustic planar array transducer is analyzed by considering the crosstalk between channels. The transmitting performance of an array transducer is frequently analyzed using the conventional finite element method (FEM). However, when the size of the array is large, the time and cost of computation using the FEM increase to almost prohibitive levels. To overcome this problem, a new equivalent circuit method (ECM) is developed to analyze the acoustic characteristics of an underwater array transducer. The ECM is validated by comparing its TVR spectrum with that analyzed using the FEM. After validation, the ECM is utilized to design the optimal structure of a planar array transducer having the broadest bandwidth. The sample analysis conducted using the ECM was approximately 1780 times faster than that by the FEM. Therefore the ECM developed in this work can facilitate the design of an underwater planar array transducer with a superior speed and efficiency compared with those achievable with the conventional numerical analysis methods such as the FEM. [ABSTRACT FROM AUTHOR]