Class IV Flextensional Transducer with a reflector

Class IV Flextensional Transducers (FTs), which are the most popular among the various FTs used for underwater sound projection, are inherently omni-directional and therefore their possible application areas are limited. In this work, we investigate the possibility of getting directional performance from a 3 kHz Class IV FT, using a reflector. Finite element modeling (FEM), with the help of a commercially available package ATILA, has been made use of. Results indicate that a parabolic reflector with a air–water interface as the reflecting surface, would give an excellent directivity of 60° (3 dB) with a front-to-back ratio better than 30 dB. Experimental results, making use of a sound-reflecting coating as the reflector has shown a directivity of 82°, with a front-to-back ratio of 21 dB. It is also observed that the reflector causes the FTs to vibrate in asymmetrical modes, the long-term implications of which needs to be studied to ensure the reliability of the device.