Sammendrag
Three common piezoelectric materials have been studied for use in pulsed wave Doppler ultrasound, where high sensitivity is required, while bandwidth is less important. A large transducer aperture, 80 mm 2 , results in a low electrical impedance, making the transducers challenging to drive with conventional electronics and cables. Air-backed transducers with electrical tuning circuitry and cable assembly were made using the piezoelectric materials Pz24, Pz27, and Pz29. Pz24 is a hard PZT, with dielectric constant of 240, the other materials are soft PZT with dielectric constants around 1000. It was found that the transducer made with Pz24 gave 2 dB better two-way sensitivity compared to those made with the other PZT-variants. The improved performance is explained by the higher electrical impedance from using pz24