基于矩形换能器空间脉冲响应的相控阵声场研究

Research on Acoustic Field of Ultrasonic Linear Phased Array Based on Spatial Impulse Response of Rectangular Planar Transducer

针对矩形换能器空间脉冲响应利用分割阵元叠加和近似方法求解,提出一种精确求解的新方法。根据矩形换能器的对称性将观察点转换到第四象限进行求解,该方法不需要远场或近轴近似,只需要坐标变换就可以得到任意长宽比的矩形换能器在不同空间点处的脉冲响应函数。通过控制各阵元的延时实现相控阵声束的偏转和聚焦,分析一维相控阵的聚焦法则,得到各阵元的延时时间;对各矩形阵元加延时控制后的空间脉冲响应叠加求和,得到相控阵聚焦时的空间脉冲响应,进而求得各空间点的声压。计算相控阵换能器在不同聚焦角度时的空间声压分布,讨论不同阵元间距对分辨力的影响。结果表明该方法可以快速准确地计算较大偏转范围内的相控阵声场。

An analytical method for calculating spatial impulse response of rectangular transducer without far-field or paraxial approximations is presented. According to symmetry of rectangular, the coordinate of observe point is transformed in the fourth quadrant. The solution using only inverse trigonometric functions and simple coordinate transformation, and impulse response of rectangular transducer with different length-width ratios can be calculated. Ultrasonic phased array can freely control the focus point position by exciting each element with independent phase delay, the focus laws of the ultrasonic l-D phased array are derived and the delay time of each element is obtained, then delay time is applied in every transducer element, and the impulse response of phased array transducer is obtained by superposition spatial impulse response of each element. Simulations are carried out for a l-D array transducer in different focusing angles, and the resolution of different distance between the transmitting elements is discussed. Results show that this method can efficiently and accurately predict the radiation field of linear phased array transducer over a wide range of steering angles.