A piezoelectric plate supporting the propagation of antisymmetric zero-order (A0) Lamb wave is proposed to be used as a hydroacoustical waveguide emitter that transmits a bulk acoustic wave into a liquid. The emitter's directional pattern has been theoretically and experimentally examined for a frequency band of 89-107 kHz. An angular acoustic beam scanning was revealed to be realized by varying the A0 wave frequency. It is shown that, unlike complicated emitting systems of phased array type, this nonmechanical scanning could be realized in a simple device. The obtained results are in a good agreement with the theoretical ones. [ABSTRACT FROM AUTHOR]