A novel method to enlarge the scanning region of a focused beamformer

Abstract

Often focused beamforming systems use the Fresnel approximation to compute the required delays. Unfortunately, such an approximation has a validity region that is very narrow around the broadside direction. To investrgate wider areas, in this paper, a novel approximation composed of the weighted terms of the conventional Fresnel approximation is presented. The attractive results (in terms of mean square error and enlargement of the validity region) obtained by applying the proposed approximation to a planar array are presented.