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以往在使用KLM等效电路模型进行压电超声换能器的性能分析时,通常忽略电极层的影响以简化计算。但这种处理方法在分析超高频换能器时会带来较大的分析误差。该文以KLM等效电路模型为基础,引入电极层声学特性参数,提出了基于二端口级联网络的计算超声换能器传递函数的方法。并用该方法计算了3种不同材料(PZT-4、PVDF和Y-36°LiNbO3)的超声换能器在不同中心频率下,电极层厚度对压电超声换能器传递函数的影响。结果表明,对于压电材料声阻抗与电极声阻抗相差较大的超声换能器,需要考虑电极层的影响。
In the past when using the KLM equivalent circuit model for the performance analysis of piezoelectric ultrasonic transducers, the influence of the electrode layer is usually ignored to simplify the calculation. However, this method of analysis will result in large analytical errors in the analysis of UHF transducers. Based on the KLM equivalent circuit model, the acoustic parameters of the electrode layer are introduced and a method to calculate the transfer function of ultrasonic transducer based on two-port cascaded network is proposed. The effects of electrode thickness on the transfer function of piezoelectric ultrasonic transducer at different center frequencies of three kinds of ultrasonic transducers (PZT-4, PVDF and Y-36 ° LiNbO3) were calculated by this method. The results show that for piezoelectric transducers, the difference between the acoustic impedance of the piezoelectric material and the acoustic impedance of the electrode should be considered in the ultrasonic transducer.