Acoustic transducers and ultrasonic transducers are the same thing: both produce longitudinal pressure waves in the surrounding medium. The difference between them is the frequency range in which they operate. Acoustic transducers operate in the audible range, from 20 Hz to 20 kHz. Ultrasonic transducers operate at frequencies above 20 kHz. However, the mechanism by which the two function is the same. The techniques for transducer design and assembly are also the same.
As transducer frequency increases the directionality increases (i.e. the beam angle narrows). As a result, most ultrasonic transducers are directional. The higher the frequency, the more directional the transducer.
There is an exception: spherical transducers provide a fully omnidirectional response regardless of frequency.
We have experience designing for frequency and beam angle, having built transducers with frequencies higher than 2 MHz and beam angles less than 1°.
If you’re looking for an ultrasonic transducer with characteristics that are not available in an off-the-shelf product, please contact us to discuss your specific requirements.