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