Diffraction loss calculation based on boundary element method for an air-coupled phased array

We present an efficient numerical method to analyze the diffraction loss of an ultrasonic air-coupled phased array transducer to an arbitrary located receiving aperture. The objective is the efficient calculation of diffraction loss for applications in which such an array is excited with arbitrary input signals on all channels for different beam steering angles. Available software, such as Field II, provide the pressure field in front of the phased transducer array, i.e. they assume a point source receiver. Our calculation method, however, is focused on directly calculating the diffraction loss to a given receiving aperture, such as a microphone or a receiving transducer, with arbitrary location and orientation. The boundary element method (BEM) is used for an efficient calculation. The entire model is implemented in the commercially available software package Mathematica V10 from Wolfram Research. Excellent agreement between calculation results and microphone measurements validate the approach. For future work, we will use this model for further optimizing the development of high-performance air-coupled phased array transducer designs.