High-Frequency, Multiband Projector Using 1–3 Connectivity Lithium Niobate Composites With an Inversion Layer

In this study, we demonstrate a sound navigation and ranging (SONAR) projector with a higher and wider frequency range using an inversion layer. Because the working frequency range of the acoustic transducers is limited, several types of transducers are required to operate at different frequencies for underwater acoustic systems. Multiband acoustic transducers have been developed to solve this problem; however, the operating frequency range is only 100–200 kHz. To overcome this, we used lithium niobate (LN) to maximize the advantage of using an inversion layer. The characteristics of LN according to the angle of the cutting direction and the characteristics of 1–3 composites were calculated, and finite element method (FEM) simulations were performed using these calculated values. The simulated and measured results of the inversion layer composite and fabricated projectors showed similar electrical impedance responses and transmitting voltage response (TVR). Resonance of the inversion layer composite occurred at 330, 680, and 1100 kHz. The fabricated projector had resonance frequencies of 390 and 790 kHz, and the working frequency range of the fabricated projector was 270–900 kHz. We expect that the developed projector will exhibit excellent performance in underwater navigation applications, such as small-scale object detection and terrain mapping.