Improved Open-Box Array Configuration for 2-D Direction Finding by Exploiting Array Motion

Recently, structured sparse arrays have been developed for improving direction-of-arrival (DOA) estimation performance on moving platforms. By employing synthetic aperture processing technology, these sparse arrays can yield a synthetic difference coarray with lots of contiguous lags, resulting in a high number of uniform degrees of freedom (DOFs). In this paper, we devise an improved open-box array (IOBA) configuration for two-dimensional (2D) DOA estimation on moving platforms. The proposed array configuration is devised by rearranging the sensors in the standard open-box array (OBA). More specifically, the IOBA is derived by placing sparsely the sensors of the OBA within a rectangular region. Under the fixed number of sensors, the IOBA configuration is uniquely determined by a closed-form expression and its number of uniform DOFs can also be analytically expressed. By exploiting array motion, the IOBA can generate more contiguous coarray lags, and thus it provides a high number of uniform DOFs than the existing sparse planar arrays. Moreover, the IOBA suffers less mutual coupling effects than the existing sparse planar arrays. Numerical results demonstrate the superiority of the proposed array over several existing sparse planar arrays.