Abstract: 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.

Key words: rectangular planar transducers;spatial impulse response;ultrasonic phased array;acoustic field simulation