The geometry of composite piezoelectric ultrasonic transducers is typically regular and periodic with one dominant length scale. In many applications there is motivation to design transducers that operate over a wide bandwidth so that, for example, signals containing a broad frequency content can be received. The device's length scale will dictate the central operating frequency of the device and so, in order to construct a wide bandwidth device, it would seem natural to design a device that contains a range of length scales. The objective of this article therefore is to consider one such transducer design and build a theoretical model to assess its performance. For the composite geometry a fractal medium is chosen as this contains a wide range of length scales. Numerical results of a theoretical model are presented. They suggest that this device would have a three-fold improvement in the reception sensitivity bandwidth as compared to a conventional composite design. Finite-element analysis provides information on the effect of poling on the device's performance. A preliminary experimental investigation was undertaken, with a Sierpinski gasket fractal transducer design, and good correlation between the simulated and experimentally measured operation was observed.
|Title of host publication||2011 IEEE International Ultrasonics Symposium (IUS)|
|Publication status||Published - 2011|