Design and Characterization Piezoelectric Acoustic Transducer for Sonar Application

Sonar system is one of the acoustic technologies that widely used in the underwater application. Sound Navigation and Ranging or SONAR is a technique to transmit and receive information using sound propagation. Besides that, sonar can be used in navigation, communication between underwater vehicles and detected the object under the surface of water. ROV or UAV will equipped with sonar transducer to recognize underwater object. The information from sonar transducer will build into images using some techniques of signal processing. It is called underwater imaging. The sharp and clear image can be obtained from high resolution and good receiving signal. Thus, the sonar is equipped with an acoustic transducer that has a capability of high sensitivity and high bandwidth. The recent sonar don’t have this capabilities, furthermore, it is bulky, high power consumption and expensive fabrication. This paper is presented design receiver of piezoelectric acoustic transducer (PAT) in small scale, inexpensive and not complex fabrication. PAT is designed using printed circuit board (PCB) as conductive part and substrate. Then, the piezoelectric material is used as sensing element and silicone glue is used to cover all conductive part. Polyvinylidene fluoride (PVDF) with thickness 110 um is transduced the vibration into electrical field. There are four differences design, with difference diameter of conductor, 8 mm, 7 mm, 6 mm, and 5 mm. Two experimental were conducted to test and characterize all PAT. They are called load test and pulse-echo method. Load test is conducted to see the behavior between mass of weight towards to PAT. Meanwhile, pulse-echo method is to characterize and see the performance of PAT. In load test result, the highest amplitude has been obtained by the design with diameter 5 mm, followed by 7 mm, 6 mm and the lowest amplitude is obtained by diameter 8 mm. The load test result has been proved using the equation 2, where the voltage is inversely proportional to their diameter of round shape. All these designs can be applied as load sensor, if used at the load weight from 0 to 50 gram. Design of PAT is used d31 mode polarization concept. This is a low cost fabrication design and high sensitivity. The design is solved the problem of an acoustic transducer with low sensitivity and narrow bandwidth. PAT is designed in small scale, and it is easy to assemble into AUV or ROV. The best design is with 5 mm, it has wide bandwidth and highest sensitivity. Then, the resonance frequency is at 125 kHz and output voltage at 555 mV.