Influence of Focal Length on Focusing Performance of EMAT Phased Arrays

摘要

Electromagnetic acoustic transducer (EMAT) phased arrays consist of multiple independent elements. The steering and focusing of the beam can be achieved by individually controlling the time delay of each element. The diameter of focal spot and the pressure distribution of the steering direction play an important role in determining the performance of the beam focusing. The pressure distribution of focusing beam would change into that of steering beam when the distance of focal length is large enough. By comparing the radiation patterns of the various focal lengths in the near field, it is learned that a short focal length is beneficial to the energy concentration and is helpful to improve the resolution of the system. The validity of the simulation model is verified by the experimental results.