Flexural axisymmetric vibrating plates with an extensive surface and stepped profile have been shown to be very useful high-power ultrasonic radiators. In fact, the stepped profile provides a highly directional or focused radiation which makes them highly efficient for gases and interphase applications. In this work we present a numerical--experimental study of the displacement distribution and the radiated field of various transducers (directional and focusing transducers working at different frequencies). The numerical model is based on a mixed finite element-boundary element method. The method basically consists of calculating the distribution of displacements of the transducers by the finite element method by using the code ATILA while the corresponding radiated field is calculated by the boundary element method by means of the code EQI. The influence of the loading medium on the displacement distribution is also calculated by the boundary element method. In this way the near and far field of the transducers is calculated as well as their directivity pattern and vibration distribution. The results obtained are compared with experimental data.