Avoiding diffraction grid effect in ultrasonic fields of 1-3 PZT polymer piezocomposite transducers

Improvement of sensitivity in ultrasonic fields of piezocomposite transduce rs is limited because of diffraction effects arising from the periodic stru cture. We present a theoretical and experimental study of ultrasonic fields of 1-3 PZT polymer piezocomposite transducers. The relation between the co mposite grid periodicity and the wavelength is critical in order to obtain a far field similar to that of homogeneous transducers. If diffraction grid effect is present, it results in an important energy loss in the higher di ffraction orders. These higher orders perturb the central field of the tran sducer because of multipath contributions to the main lobe caused by reflec tions from the boundaries of the test sample.