Affiliation:
1. Center for Telecommunication Studies, Pontifical Catholic University of Rio de Janeiro, Rio de Janeiro 22451-900, Brazil
2. Department of Mechanical Engineering, São Carlos School of Engineering, University of São Paulo, São Carlos 13566-590, Brazil
Abstract
Ultrasonic waves generated and received by electromagnetic acoustic transducers (EMATs) are advantageous in non-destructive testing, mainly due to the ability to operate without physical contact with the medium under test. Nevertheless, they present a main drawback of less efficiency, which leads to a lower signal-to-noise ratio. To overcome this, the L-network impedance-matching network is often used in order to ensure maximum power transfer to the EMAT from the excitation electronics. There is a wide range of factors that affect an EMAT’s impedance, apart from the transducer itself; namely, the properties of the specimen material, temperature, and frequency. Therefore, to ensure optimal power transfer, the matching network’s configuration needs to be fine-tuned often. Therefore, the automation of the laborious process of manually adjusting the network is of great benefit to the use of EMAT transducers. In this work, a simplified one-parallel-element automatic matching network is proposed and its theoretical optimal value is derived. Next, an automatic matching network was designed and fabricated. Experiments were performed with two different EMATs at several frequencies obtaining good agreement with theoretical predictions. The automatic system was able to determine the best configuration for the one-element matching network and provided up to 5.6 dB gain, similar to a standard manual solution and considerably faster.
Funder
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brasil
the Carlos Chagas Filho Foundation for Research Support of Rio de Janeiro State (FAPERJ), Brazil
Brazilian National Council for Scientific and Technological Development, CNPq
Subject
General Environmental Science
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