Generation of ring-shaped acoustic pressure fields based on the bottle beam concept using airborne ultrasonic phased arrays.

This paper verifies the feasibility of generating acoustic ring beams-defined as ring-shaped, high-pressure distributions localized around a target plane-using an airborne ultrasonic phased array. Physical experiments using a 40 kHz airborne ultrasonic phased array confirmed that the diameter of the proposed acoustic ring beam is much larger than the wavelength. The proposed method is expected to open up possibilities for applications, such as the acoustic cloaking of large objects.