Effect of the sound field structure on array signal gain in a multipath environment

A wide-aperture, horizontal line array receiving a low-frequency, long-range signal is considered. It is shown that the sound field structure as manifested by amplitude nonhomogeneity and the wave-front corrugation can reduce the performance of a conventional linear beamformer. Beamformer expressions that explicitly show the effects of amplitude nonhomogeneity and wave-front corrugation in a multipath environment are given. The limitations of some array algorithms that are inappropriate for a multipath environment are indicated. Array signal gain and side-lobe suppression relations for an ocean multipath environment are generalized from similar relations that are not valid in an ocean multipath environment.