Application of hexagonal arrays in generation and steering of limited diffraction beams

Limited diffraction beams (LDB´s) have narrow beamwidth and long depth of field. These features make these beams potential candidates for high resolution diagnostic imaging. LDB´s can be generated using either annular or two-dimensional (2-D) array transducers. For real time imaging systems, where rapid beam steering is required, 2-D arrays are preferred because the beams of such arrays can be steered electronically. The major disadvantage of ordinary 2-D arrays is the complexity associated with the large number of elements required to produce a beam with sufficient accuracy. Taking advantage of the fact that common LDB´s have circular symmetry, it can be shown that these beams can be produced-by hexagonal arrays using 13.4% less elements than what is required in the case of ordinary 2-D arrays. Here, we study the generation, and in particular, steering of the LDB´s by hexagonal arrays