Permanent magnet is widely used as one of the three elements of electromagnetic acoustic transducer (magnet, coil, tested specimen). However, due to the immutability and non-uniformity of the permanent magnet magnetic field, the electromagnetic acoustic transducer (EMAT) will produce other unwanted modes, which will affect the purity of the targeted mode in signals. Therefore, the multi-mode problem of EMAT is still an important issue to be solved. In order to solve this problem, a new type of directional magnetic-concentrator-type electromagnetic acoustic transducer (D-MC-EMAT) is proposed to generate a single S₀ mode in plates. The magnetic concentrator is added to the traditional EMAT to guide and concentrate the magnetic field generated by the magnet and remove the unwanted A₀ mode. Both finite element simulation and experiments proved that the mode selectivity of proposed D-MC-EMAT improved by adding the magnetic concentrator, and transducer characteristics and defect inspection experiments were carried out. Finally, the structure of D-MC-EMAT was optimized by an orthogonal experiment and the optimal parameter combination was confirmed.

永磁体被广泛用作电磁声换能器（磁体，线圈，被测样品）的三个元素之一。但是，由于永磁体磁场的不变性和不均匀性，电磁声学换能器（EMAT）将产生其他不需要的模式，这将影响信号中目标模式的纯度。因此，EMAT的多模式问题仍然是需要解决的重要问题。为了解决这个问题，提出了一种新型的定向磁选器型电磁声换能器（D-MC-EMAT），在平板中产生单一的S ₀模式。磁性集中器被添加到传统的EMAT中，以引导和集中由磁体产生的磁场，并去除不需要的A ₀模式。有限元模拟和实验均证明，通过添加磁选机可以改善所提出的D-MC-EMAT的模式选择性，并进行了换能器特性和缺陷检查实验。最后，通过正交试验优化了D-MC-EMAT的结构，并确定了最佳的参数组合。