Theoretical research and experimental demonstration of the possibility of creating a plane-wave regime using a large piezoelectric source.

The possibility of experimental realization of an acoustic field in the form of a traveling plane wave is studied with the purpose of measuring the absorption coefficient and the speed of sound in a propagation medium. To do so, it is proposed to use a flat piezoelectric source and to perform measurements in the pulsed mode at short distances from the radiating surface. As a result of theoretical modeling based on the exact solution of the wave equation on the axis of a circular piston radiator, spatial and time intervals for the existence of a plane wave mode are revealed. It is shown that the proposed method allows to measure the absorption coefficient of ultrasound in liquids and soft biological tissues in the megahertz frequency range using radiators of centimeter sizes.