MULTI-HORN MATCHING PLATE FOR ULTRASONIC TRANSDUCERS

The problem of matching a thick piezoelectric transducer to an air med ium is considered and it is concluded that a suitable matching device can be designed and built in the form of a rigid plate, a few millimet res thick and pierced by a closely packed array of horn-shaped channel s, the wide mouths of the horns facing the external world and the narr ow throats facing the transducer. Design parameters, particularly the spacing between the multi-horn plate and the transducer surface, are f ound to be quite critical, but well within ordinary manufacturing capa bilities. Methods of fabricating the multi-horn plates are described a nd measured results presented. The measured performance agrees quite w ell with design calculations. The experimental plates show a gain of a lmost-equal-to 10 dB over a frequency range from almost-equal-to 30 to 100 kHz. Similar matching plates for other frequency ranges can be ma de.