HALF INVERTED NESTED ARRAYS WITH LARGE HOLE-FREE FOURTH-ORDER DIFFERENCE CO-ARRAYS

Sparse arrays with fourth-order cumulant processing can identify up to O(N4) source directions with only N physical sensors. To achieve this property, the fourth-order difference co-array is preferable to own a contiguous segment with no holes. However, existing sparse array designs either have holes in the co-array of size O(N4) or own fewer than O(N4) elements in the hole-free co-array. This paper proposes the half inverted nested array (HINA), which consists of a nested array and an inverted, scaled, and shifted nested array. By maximizing the size of the co-array, it can be shown that HINA with the optimal parameters possesses a hole-free fourth-order difference co-array of size O(N4). Numerical examples demonstrate the improved DOA estimation performance of HINA. © 2022 IEEE