用于电磁超声检测系统的宽带匹配电路的设计

Design of Broadband Matching Circuit for EMAT Detecting System

电磁超声换能器是一种新型超声波发射接收装置,与传统的压电式换能器相比具有无需声耦合剂、无需对待测物预处理等显著优点。但是该装置换能效率很低,必须通过改善电磁超声电路系统的性能来增加接收信号的强度。为了提高电路系统的能量转换效率,设计了基于传输线理论的电磁超声宽带匹配电路。实验表明:所设计的匹配电路能够使发射电路输出功率增加60%,有效提高了检测系统的整体效率,为电磁超声技术的工程应用奠定了基础。

Electromagnetic acoustic transducer （EMAT） is a new kind of ultrasonic transmitting and receiving device. Comparing with the conventional piezoelectric transducer, it possesses several remarkable advantages, such as free of acoustic couplant, needless of pretreatment of the test piece, etc. As the transduction efficiency of the EMAT is quite low, however, it is often required to improve the EMAT electronic system so that the strength of the receiving signal could be raised. In order to increase the efficiency of the electronic system, designed electromagnetic-acoustic matching circuits based on transmission line theory. Experiments proved that the matching circuits designed were able to increase the output power of the transmitting circuit by 60%, which effectively boosted the whole efficiency of an EMAT detecting system, and provided a basis for application of the electromagnetic acoustic technique.