Beam pattern formulation and analysis for wide-band beamforming systems using sparse arrays

This communication addresses the evaluation of beam patterns (BPs) in active beamforming systems using wide-band signals and sparse arrays. Usually, BPs are computed under a narrow-band hypothesis according to which a simple analytical and closed-form equation can be used. In this communication, with reference to imaging applications, the BP for wide-band signals is redefined on the basis of beam-signal maxima, and a quasi-closed form of the analytical formulation is achieved for any inter-element spacing. It can be noticed that, under wide-band conditions, the height of these grating lobes can be predicted and that depends only on the pulse duration and on the number of array elements, but does not depend on the spacing between elements. As a result, the proposed quasi-closed form supports the design of very sparse arrays that show beam-pattern profiles of great interest for imaging applications. (C) 1997 Elsevier Science B.V.