Abstract: An automatic impedance matching system that can read the input impedance of an EMAT electrical circuit and automatically select the appropriate impedance matching by combining components from a built-in selection of matching circuitry. A Vector Network Analyzer or similar impedance measuring circuit is connected to the EMAT electrical circuit and measures the impedance of the EMAT RF coil, coil cable, and conductive material to be inspected at a given material lift-off, and relies on the information to the system processor. The processor uses this information to adjust the overall impedance by selecting appropriate capacitors and transformer taps on a programmable impedance matching circuit connected between the system pulser/receiver and the RF coil cable. The system can work in either pulse-echo (same transmitter and receiver) or pitch-catch (different transmitter and receiver).

Abstract: A high-voltage pulser circuit for Electromagnetic Acoustic Transducer (EMAT) coils using a Capacitive Discharge push-pull converter. The present invention relates in particular to the operation of the converter into an Electromagnetic Acoustic Transducer (EMAT) differential coil. The present invention reduces ringing of the coil current resulting in a smaller blind zone and a well-defined broadband ultrasonic wave from the coil. The pulser can be used to generate one or more cycles and work in either pulse-echo (same transmitter and receiver) or pitch-catch (different transmitter and receiver).

Abstract: A high-voltage pulser circuit for Electromagnetic Acoustic Transducer (EMAT) coils using a Capacitive Discharge push-pull converter. The present invention relates in particular to the operation of the converter into an Electromagnetic Acoustic Transducer (EMAT) differential coil. The present invention reduces ringing of the coil current resulting in a smaller blind zone and a well-defined broadband ultrasonic wave from the coil. The pulser can be used to generate one or more cycles and work in either pulse-echo (same transmitter and receiver) or pitch-catch (different transmitter and receiver).