New Array Designs for DoA Estimation of Non-Circular Signals With Reduced Mutual Coupling

Recently, many sparse arrays are proposed to achieve increased uniform degrees of freedom (uDoFs) for the direction of arrival (DoA) estimation of non-circular sources. In light of this recent attention, the high number of uDoFs is the primary motivation for designing those sparse array structures. Although both the number of uDoF and mutual coupling can influence the DoA estimation performance. However, mutual coupling is not considered in many of those sparse array configurations. In this article, two optimized shifted coprime arrays with sum-difference coarrays, called OSCAwSDCa-I and OSCAwSDCa-II, are proposed to reduce mutual coupling. The OSCAwSDCa-I and OSCAwSDCa-II are obtained by rearranging actual sensors of the augmented coprime array. The proposed array designs have closed-form expressions for their sensor locations and achievable uDoFs. Additionally, it is proven that the first three weights of OSCAwSDCa-II are independent of the array size. Moreover, the number of virtual sensors co-locating at the same lag is reduced. Consequently, smaller weight values are obtained, resulting in more robustness against mutual coupling. Finally, extensive simulations show that OSCAwSDCa-I and OSCAwSDCa-II can achieve comparable uDoFs concerning the existing array structures. In the presence of strong mutual coupling, simulation results demonstrate the robustness of OSCAwSDCa-II more than other compared configurations.