Analysis of resolution for an amplitude-steered array

In 1976. Hughes and Thompson introduced the idea of steering the maximum re sponse of a linear array by amplitude weighting the output signals of the e lements, thus eliminating the need for time delays or phase-shift networks. Currently that amplitude-steered array concept is being extended to a broa dband two-dimensional array that can be used for real-time three-dimensiona l imaging. In shifting the use of the amplitude-steered array from underwat er acoustic communications to imaging, we must consider different issues of the array's performance such as lateral and axial resolution. For the line ar amplitude-steered array, we show that both lateral and axial resolution are limited by the length of the array. The dependence of axial resolution on the length of the array is a unique feature of the amplitude-steered arr ay, leading to an interesting tradeoff between lateral and axial resolution . A theoretical basis for the dependence is developed and simulation result s are given. (C) 2000 Acoustical Society of America. [S0001-4966(00)03705-X ].