The RF transformer application for ultrasound excitation: the initial study

Practical aspects of design and application radio frequency (RF) transformers in an ultrasonic system excitation channel are analysed. Design steps are discussed for those willing to design their own transformer an for excitation channel. Investigation has been carried out on what generator parameters can be obtained if instead of a purely active output stage the impedance matching RF transformer is used. It is assumed that a low output impedance active stage is coupled to a relatively high impedance ultrasonic transducer. An air coupled ultrasonic transducer has been used as a reference for the calculations. Several materials are considered for the RF transformer core and possible candidates and their properties for 10kHz to 10MHz frequency range are listed. The algorithm for performance investigation using only manufacturer parameters and the Matlab modeling has been presented. The experimental study has confirmed RF transformer suitability as a voltage step-up component for ultrasonic transducer excitation. The 0.1…10 MHz passband is achieved. The results obtained at different transmitted power levels (from 50W to 0.5W) indicate there is only slight reduction in the bandwidth. The presented configuration can be used for ultrasonic transducer excitation using an arbitrary waveform generator.