High efficiency, multiple layer ZnO acoustic transducers at millimeter-wave frequencies

Abstract
We have fabricated multiple layer ZnO acoustic transducers for highly efficient sound wave generation at millimeter-wave frequencies. The transducers consist of half-wave-thick layers of ZnO with alternating crystal structure. The two-way untuned conversion loss values were 27 dB near 29 GHz and 50 dB at 96 GHz measured at liquid nitrogen temperatures.