Tapered transmission line technique based graded matching layers for thickness mode piezoelectric transducers

Ramadas, Sivaram Nishal and O'Leary, Richard and Mulholland, Anthony and Hayward, Gordon and Mackintosh, Allan and Troge, Alexandre and Pethrick, Richard; (2009) Tapered transmission line technique based graded matching layers for thickness mode piezoelectric transducers. In: 2009 IEEE International Ultrasonics Symposium. IEEE, ITA, pp. 1695-1698. ISBN 9781424443895 (https://doi.org/10.1109/ULTSYM.2009.5441463)

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Abstract

Conventionally, in order to acoustically match thickness mode piezoelectric transducers to a low acoustic impedance load medium, multiple quarter wavelength (QW) matching layers are employed at the front face of the device. Typically a number of layers, 2-4 in number, are employed resulting in discrete impedance steps within the acoustic matching scheme. This can result in impedance matching with limited bandwidth characteristics. This paper investigates the application of tapered transmission line filter theory to implement a graded impedance profile, through the thickness of the matching layer scheme, to solve the impedance mismatch problem whilst accounting for enhanced transducer sensitivity and bandwidth.