Compensation of a transmitter´s radiation pattern for synthetic transmit aperture acoustic imaging

In an acoustic imaging system, ultrasonic transmitters always have uneven signal strength in the imaging space. Phase changes also occur depending on the distance and direction. In this paper, a new approach to decrease the effect of a transmitter´s radiation pattern in acoustic imaging is proposed. We compensated for the transmitter´s radiation pattern and reconstructed acoustic images using the Synthetic Transmit Aperture imaging technique. The compensation was based on the radiation pattern obtained from real measurements and using a Wiener filter. The purpose of the work was to compensate for a nonideal radiation pattern of the ultrasonic transmitter for both phase and amplitude aspects. An airborne imaging experiment was conducted using a two-dimensional (2D) receiver array and a 2D transmitter array to verify the effectiveness of our proposed method. The results showed an improvement in the vertical angular resolution of reconstructed three-dimensional images.