Dept. of OAE, IEMN, Valenciennes Univ., BP 311 Le Mont-Houy, 59304 Valenciennes, France
In this paper, a new calculation scheme is proposed to compute the nearfield and the farfield directivity pattern of such arrays including interactions and without assumptions concerning the displacement field of the transducer radiating surface. For this purpose, using the finite element method (FEM), the farfield directivity pattern of a part of the array (2Q +1 transducers) is computed using dipolar dampers and a previous described extrapolation algorithm [Assaad et al., J. Acoust. Soc. Am. 94, 562--573 (1993)]. This part consists of an active elementary transducer (electrically driven) mounted between 2Q passives (electrically grounded) neighboring transducers. Then, the radiation field of a finite phased and focused array (N elements) can be obtained by summing up the farfield directivity patterns of the 2Q + 1 transducer sets weighted by the classical term used to take account of the geometrical and electrical phase shifts.