A 2D Super-Nested Array Based on the Fourth-Order Difference Coarray

Super-nested arrays are receiving growing attention due to their large degrees of freedom (DoF) and the reduced mutual coupling between the array elements. The array has been proposed for one-dimensional direction of arrival (1DDoA) estimation and is a potential candidate for two-dimensional (2D-DoA) estimation. In this paper, a new 2D super-nested array (2DSNA) is proposed by combining two parallel super-nested arrays spaced by λ/2. The analytical expressions for the secondorder and fourth-order difference coarrays are derived. The work also shows that the second-order and fourth-order difference coarrays are hole-free. The proposed configuration has lower mutual coupling effect due to super-nested structure and large DoF. Furthermore, simulation results validate the robustness and accuracy of the DOA estimation performance with the proposed configuration.