The responsivity of an ultrasonic transducer is an important parameter in evaluating its effective frequency band, the electroacoustic conversion efficiency, and the measurement capability of the system. The determination of the responsivity of a traditional immersion or contact piezoelectric transducer has been well investigated. However, due to the high attenuation of waves propagating in air and the large acoustic impedance mismatch between the active piezoceramic material and the load medium, there are few reports of the calibration of an air-coupled piezoelectric transducer. In this work, we present a comparative method of measuring the responsivity of an air-coupled transducer: the air-coupled transducer is used to receive a broadband pulse signal to evaluate its frequency spectrum, and a toneburst signal with known vibration displacement is measured by the air-coupled transducer in order to calibrate the amplitude of the responsivity. The effects of transmitter responsivity, input pulse characteristics, attenuation, and diffraction are taken into account to improve the accuracy of the responsivity determination. In addition, the measurement of the amplitude of the responsivity by comparing the measured displacements avoids the complicated task of characterizing the effects of electrical equipment. The determined responsivity is checked by comparing the measured displacements using different methods at different frequencies in order to evaluate its frequency spectrum and by measuring the nonlinearity parameters of the material to evaluate its amplitude. The agreement between results obtained using different methods demonstrates that the calibrated responsivity of the air-coupled transducer is valid, and the proposed method is effective.

中文翻译：

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使用比较方法确定空气耦合压电传感器的响应度：理论和实验。

超声换能器的响应度是评价其有效频带、电声转换效率和系统测量能力的重要参数。已经对传统浸入式或接触式压电换能器的响应度的确定进行了很好的研究。然而，由于在空气中传播的波的高衰减以及有源压电陶瓷材料与负载介质之间的较大声阻抗失配，关于空气耦合压电换能器校准的报道很少。在这项工作中，我们提出了一种测量空气耦合换能器响应度的比较方法：空气耦合换能器用于接收宽带脉冲信号以评估其频谱，并且通过空气耦合换能器测量具有已知振动位移的音爆信号以校准响应度的幅度。考虑了发射机响应度、输入脉冲特性、衰减和衍射的影响，以提高响应度确定的准确性。此外，通过比较测量的位移来测量响应度的幅度避免了表征电气设备影响的复杂任务。通过在不同频率下使用不同方法比较测量的位移以评估其频谱并通过测量材料的非线性参数以评估其振幅，来检查确定的响应度。