Abstract: The invention relates to underwater mines countermeasures methods and devices that can be employed from a helicopter.It consists in using the body (101) of a known passive heli-winched sonar, fitting to it emitting antennas (105, 106) arranged in this body parallel to its axis and a receiving antenna perpendicular to this axis and formed of two articulated arms (107, 108) that can be retracted inside the body. Two other arms (114, 113) that can be retracted into the body have propulsion means (111, 112) at their free ends, to allow the body to be stabilized about its axis.The invention makes it possible to employ lightweight helicopters for underwater mines countermeasures, allowing the mines to be relocated and, if appropriate, destroyed without having to backtrack.

Abstract: A simultaneously transmitting and receiving multipath sonar antenna comprs an acoustic lens which focuses received acoustic beams on a focal surface, and at least two intercalated groups of piezoelectric transducers disposed on the focal surface of the lens. The transducers of the at least two groups are tuned to different frequencies, and the transducers of each group are excited with a phase difference between one column and the next column of the same group.