Abstract:

In order to solve the problems of high side-lobe and weak suppression of end directional interferences for a linear array, the virtual sources interference method is modified and introduced into the weighted beamforming of uniform linear array. A set of general and feasible solution is proposed to distribute virtual sources and initialize parameters. Secondly, the approaches are improved of the main-lobe guidance, the covariance matrix estimation, the weighted coefficients normalization and so on in the optimizing iteration. Then, the weighted beamforming method can achieve const low side-lobe level at the full-space directions, and can suppress the end directional continuous strong interferences effectively. Therefore, it is suitable for the towed linear array case especially. Based on numerical simulations and sea-trial data instances, compared with the common weighted and un-weighted beamforming methods, the effectiveness of this modified method is demonstrated from the aspects of directivity pattern, two-dimensional spatial spectrum, pre-beamforming output and so on, where the suppression capability analysis of end directional interferences is emphasized.

Key words: constant low side-lobe level, weighted beamforming, virtual sources interference method, uniform linear array, end directional interference