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.

Abstract: A sonar system capable of identifying submerged objects near the ocean floor is provided. Transmitting and receiving transducers are mounted on a common support including an arrangement for pivoting the transducers around a vertical axis. The signals from the receiving transducer are amplified and appropriate phase shifting is provided to form very narrow, close monitoring channels focused in the Fresnel region of the transducer. Sampling circuitry for sequentially sampling the monitoring channels provides a signal for a CRT display and a memory lens. Possible applications include the detection and identification of influence ground mines.