换能器的匹配

关于换能器的匹配层阻抗值的选择，已有三种计算公式。由于三种公式所计算的阻抗值有较大差异，为了比较，以选择合理的匹配层阻抗值，本文用Ｍａｓｏｎ等效电路直接计算换能器的频带及波形，比较了用三种公式所得阻抗值匹配的换能器的状态。并计算了匹配层厚度对换能器波形的影响。计算结果与实验结果吻合很好。可为匹配层材料及厚度的选择提供理论依据。

Matching layer of the transducer

In the medical ultrasonic test and NDT,It is often to use matching layer to improvewave shape and sensitivity of the transducer. There are three different formulas in theoriesof the matching layer. The impedance values of the matching layer calculated from different formulas are very different.We use Mason equivalent circuit to calculate the frequency band, the wave form and the sensitiyity of the transducer. Theoretical and experimental results are in agreement. It proyides a good basis for choosing the matching mediaand the thicknesses of the matching layer.