Acoustic (Ultrasonic) Non-Diffracting Beams: Some Theory, and Proposals of Acoustic Antennas for Several Purposes

Michel Zamboni-Rached, Erasmo Recami

On the basis of a suitable theoretical ground, we study and propose Antennas for the generation, in Acoustics, of Non-Diffracting Beams of ultrasound.  We consider for instance a frequency of about 40 kHz, and foresee fair results even for finite apertures endowed with reasonable diameters (e.g., of 1 m), having in mind various possible applications, including remote sensing.  We then discuss the production in lossy media of ultrasonic beams resisting both diffraction and attenuation.  Everything is afterward examined even for the cases in which  high-power acoustic transducers are needed (for instance, for detection at a distance —or even explosion— of buried objects, like Mines).