Investigation of the ultrasonic transducer suitability for spread spectrum systems

Investigation of the ultrasonic transducer properties with aim for spread spectrum (SS) signals application is presented. Structure and parameters of dedicated ultrasonic data acquisition system are presented. Transducer impedance was measured and interaction with excitation generator was evaluated for attainable power delivery efficiency and bandwidth. For transducers planned to be used in imaging, the directivity of the transducer was evaluated in reflection mode. Steel ball of 5 mm diameter was used as reflector. X-Y scan was performed using fixed step, while Z step was adapted to on-axis pressure variation. Data processing flow for automated directivity calculation is outlined. Obtained X-Z, Y-Z, X-Y directivity plots are presented for 20 MHz focused transducer. Investigation of the spectral content versus off-axis coordinate is presented. Pressure field produced by transducer was measured using the needle hydrophone at several Z-planes for wideband 5 MHz transducer.