Optimization of piezoelectric ultrasound emitter transducers for underwater communications

Abstract

Ultrasound transducers are typically based on piezoelectric materials, due to their good response at high frequencies. Depending on the application, ceramics, polymers and composite materials can be used. In this work, an optimization study of ultrasound transducers for underwater communications is addressed, focusing on a piston type emitter transducer operating in thickness mode (d 33). The piston is constituted by an active element disk with optimized dimensions. It is discussed how the acoustic impedance, thickness, resonance frequency and structure affect the transducer performance. This work allows a better understanding of the emitter transducer characteristics allowing reaching the optimum point of operation for specific applications. Focusing on underwater communication, the acoustic channel is defined and the transducer is optimized by finite element computer simulations. The results were compared with experimental tests, which show that four-layer structures increase up to 16 dB in performance versus single-layer.

Underwater acoustic modem with streaming video capabilities

“…For a wideband response, the piezoelectric material as to present an acoustic impedance near to the medium acoustic impedance (around 1.5x10 6 kg/m²s), the nearest better will be the energy transference from the transducer to the medium, reducing the signal distortion and attenuation. Therefore, it was selected the PVDF polymer material in piston configuration transducer, since it is an interesting material due to the low acoustic impedance (3.3x10 6 kg/m²s) and price [16] [23]. Another advantage of the PVDF is the power consumption in comparison to the common Ceramic materials such as Lead Zirconate Titanate (PZT), Lead Titanate (PT), Lead Magnesium Niobate (PMN) and Lead Zinc Niobate (PZN) [24].…”

“…In [14] the authors presented an acoustic Field Programmable Gate Array (FPGA) based modem, operating at frequencies between 0.1 and 1 MHz, for distances ranging between 50 m and 100 m. Using a Binary Phase Shift Keying modulation with 800 kHz carrier frequency, the system archived a 80 kbps data rate. In [15] [16] [17] a polymer-based directional transducer was developed with a bandwidth between 0.5 and 1 MHz, and poolexperimental results have shown a data-rate of 1 Mbps with a simple modulation scheme such as OOK at a distance of 20 m.…”

Development of a 1 Mbps low power acoustic modem for underwater communications

“…This study is focus on PVDF polymer piston type transducer, since it is an interesting material due to the low acoustic impedance (3.3x10 6 kg/m²s) and price [9] [10]. With values near to the water acoustic impedance (around 1.5x10 6 kg/m²s), it is possible to minimize the acoustic signal distortions and allow a better acoustic energy transference from the transducer to the medium, resulting in a reduction of the acoustic energy accumulated inside the transducer.…”

“…The solution for the lack of force and for the acoustic energy retained inside the active element is the use of multilayers structure with thin films [9]. From equation 3, by reducing the active element thickness it is possible to increase the force applied to the medium, and by equation 5, reducing the active element thickness results in a decrease of the internal reflected wave propagation delay.…”

Application of ultrasound in medicine part ii: the ultrasonic transducer and its associated electronics

“…An additional problem in lineal transducers is the multi-coaxial cable. It can suffer from interruptions on some lines from sudden twists or rough use, which modify the continuity of the image produced in the equipment [66] [67]…”