METHOD OF EXCITING AND RECEIVING SYMMETRIC AND ANTISYMMETRIC WAVES IN THIN WAVEGUIDES

摘要

FIELD: physics.;SUBSTANCE: method comprises mounting an ultrasonic transducer on the surface of a waveguide, said transducer being connected to an electrical signal generator and receiver; applying voltage to the transducer such that a volume wave, e.g. a longitudinal wave, is emitted in the waveguide in the direction perpendicular to the axis of the waveguide; an echo signal generated by the normal wave arising in the waveguide due to partial transformation of the volume wave to a normal wave is then received, amplified and processed; further mounting, on the opposite side of the waveguide coaxial to the first transducer, an ultrasonic transducer whose acoustic parameters differ from that of the first transducer by ±5%, wherein electrical connection of both transducers is such that the phases of emitted and received signals either match (for the case with symmetric normal waves) or are oppositely signed (for the case with antisymmetric normal waves), for which, when emitting and receiving symmetric normal waves, both transducers are electrically connected in parallel, and when emitting and receiving antisymmetric normal waves, the transducers are excited with voltage of opposite polarity and both transducers are connected to different inputs of a differential amplifier or both transducers are electrically connected in parallel, and their piezoelectric elements are polarised in opposite directions.;EFFECT: high amplitude of the received normal wave.;4 dwg