Study on the Steering Capability of A Meander-line Coil EMAT

Abstract

Electromagnetic acoustic transducers (EMATs) are well-established as a means of ultrasonic wave generation and reception without the use of a mechanical coupling. When comprising a bias magnetic field and a meander-line coil (MLC), these waves propagate at an angle normal to the emission surface. With the appropriate frequency, the propagation pathway of these ultrasonic waves can be steered to a particular angle. This paper presents the methodology used to find the steering limit of an MLC EMAT and the results from simulations and experimental validations on aluminium. The results show that the maximum shear wave amplitude occurred at around 30°, the steering limit was approximately 50° and the simulations were validated by the experimental set-up to a satisfactory degree.