Development of a Dual-Layer Structure for Cymbal Transducer Arrays to Achieve a Wider Bandwidth

Abstract

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.

Design of Piezoelectric Acoustic Transducers for Underwater Applications

“…When configuring an array from a single transducer, the pitch of the transducer is designed as half wavelength of the resonant frequency. In Figure 6 , the resonant frequencies of the first layer and second layer are different to further enhance the output characteristics of the transducer array [ 14 ].…”

“…Tonpilz transducers are not based solely on a single piezoelectric material but are designed by adding a mass to the front of and behind the piezoelectric material. Another study expanded the transducer bandwidth by changing the physical properties of the piezoelectric material in an additionally designed transducer [ 14 ]. Research related to the tonpilz transducer is introduced in Section 4 .…”

“…The attached transducer array consists of tonpilz transducers. Previously, the transducer was designed according to a pitch suitable for the target frequency to form an array; however, recently, more sophisticated arrays have been proposed [ 14 , 15 ]. The transducer is composed of dual layers; thus, each layer has a different resonance.…”

“…In another example, when designing an array, the resonance frequencies of transducers facing each other were designed. In the transducer array study, a pitch adjustment technique was applied to widen the transducer’s bandwidth [ 14 , 15 ].…”

Selection of a Potting Material and Method for Broadband Underwater Cymbal Arrays

“…The array is a double-layered cymbal array, as shown in Figure 2 , where the blue area is the cymbal transducer and yellow area is an aluminum frame. The dual-layer array structure could provide a wider bandwidth by reducing the center-to-center spacing between cymbal transducers in the array compared with that of conventional single-layer array structure [ 15 ]. The upper and lower layers have five and four cymbals, respectively.…”