Low insertion loss air-coupled ultrasonic transducer with parallel laminated piezoelectric structure

Air-Coupled Low Frequency Ultrasonic Transducers and Arrays with PMN-32%PT Piezoelectric Crystals

Air-coupled ultrasonic techniques are being increasingly used for material characterization, non-destructive evaluation of composite materials using guided waves as well as for distance measurements. Application of those techniques is mainly limited by the big losses of ultrasonic signals due to attenuation and mismatch of the acoustic impedances of ultrasonic transducers and air. One of the wa...

New Designs of Focussed Air-coupled Ultrasonic Transducer

The paper describes new developments in air-coupled ultrasonic transducers that can be used to focus energy in air. All transducers to be described are based on a capacitive design, using a rigid backplate and a thin polymer membrane. There are three approaches that can be used to achieve focussing, all of which are described: focussing with a mirror, using curved back-plates, and linear phased...

Micromachined piezoelectric ultrasonic transducer with ultra-wide frequency bandwidth

Air-Coupled Ultrasonic Receivers with High Electromechanical Coupling PMN-32%PT Strip-Like Piezoelectric Elements

For improvement of the efficiency of air-coupled ultrasonic transducers PMN-32%PT piezoelectric crystals which possess very high piezoelectric properties may be used. The electromechanical coupling factor of such crystals for all main vibration modes such as the thickness extension and transverse extension modes is more than 0.9. Operation of ultrasonic transducers with such piezoelectric eleme...

Horn-Type Piezoelectric Ultrasonic Transducer: Modelling and Applications