Improving the SNR of angled SV-wave EMATs using staggered meander-line coils configuration

Abstract

ABSTRACT This paper proposes a modified angled shear vertical (SV) wave electromagnetic acoustic transducer (EMAT)with two staggered meander-line coils (MLCs). In the modified EMAT, the transmitting MLC and receiving MLC are staggered in the vertical direction and with a horizontal offset, and this offset equals half of the horizontal distance between the center of the two adjacent MLC conductors, and there is no conductor overlapped area between the two MLCs. We establish a finite element model for the angled SV wave EMAT to investigate the advantages of this modified EMAT and compare it with the three traditional EMAT configurations. Subsequently, we investigate the influences of the conductor overlapped area of the transmitting MLC and receiving MLC and vertical distance between the two MLCs in the modified EMAT on the conversion efficiency and signal-to-noise ratio (SNR). The results indicate that the modified MLC EMAT can suppress the noise from the pulse power generator and reduce the dead zone in ultrasonic detection efficiently. Compared with the three conventional types of the MLC EMAT, the amplitude of the received ultrasonic wave signal and its SNR of the modified MLC EMAT can be enhanced by 31.4% and 10.1dB, respectively.