Research on Virtual Array Transform Method of Uniform Bicircular Array

Abstract

In order to solve the problem of insufficient target discrimination and spatial resolution caused by the limited aperture of a bicircular array in the aerial sonar system, a virtual array transform method that could expand the aperture of the bicircular array was proposed. In the proposed method, the relationship between the signal model of the bicircular array in the modal domain and that of the double linear array in the array element domain was analyzed, and the sampling matrix and phase rotation matrix were designed to transform the uniform bicircular array into a uniform double linear array. Then, the effects of array element position error, mutual coupling between array elements, and observation angle error in the actual bicircular array were considered. By using the least square criterion, an optimization model was proposed to approximate the actual bicircular array to a uniform double linear array. The iterative solution method was also given. Compared with the synthetic aperture method, the proposed method is a preprocessing of the array manifold and has no special requirements for the motion characteristics of the array in the actual application scene. Compared with the transform method in the modal domain, the proposed method can reflect the array element spacing and the spacing between two linear arrays of the double linear array and make full use of the advantages of the double linear array compared with the single linear array. The results of the simulation experiment and water tank experiment show that the aperture of the bicircular array is expanded; the main lobe of the virtual array beam pattern is narrower, and the sidelobe is lower than that of the bicircular array beam pattern, which effectively improves spatial resolution and target discrimination.

Keywords

• bicircular array
• virtual array
• aperture expansion
• spatial resolution
• target discrimination