A Simplified One-Parallel-Element Automatic Impedance-Matching Network Applied to Electromagnetic Acoustic Transducers Driving

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...

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Bibliographic Details
Published inAutomation (Basel) Vol. 4; no. 4; pp. 378 - 395
Main Authors Andrade, João Pedro T., Bazan, Pedro Leon F. C., Medeiros, Vivian S., Kubrusly, Alan C.
Format Journal Article
LanguageEnglish
Published Basel MDPI AG 01.12.2023
Subjects
Acoustic impedance
Acoustics
Automation
Configurations
Efficiency
EMAT
Impedance matching
Magnetic fields
Maximum power transfer
Nondestructive testing
Signal to noise ratio
Temperature
Transducers
Variables
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Summary: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.
ISSN:2673-4052
2673-4052
DOI:10.3390/automation4040022