A symmetric extended-transformed nested array for localization of mixed far-field and near-field sources

In this study, A groundbreaking sparse array designed for the precise localization of both near field (NF) and far field (FF) mixed sources are proposed, which can provide high degrees of freedom (DOFs) as well as tolerate heavy levels of mutual coupling. We commence by partitioning the compact subarray of the transformed nested array into three distinct segments, subsequently shifting them to the right to augment the DOFs. and then relocating sensors of transformed nested array to mitigate heavy levels of mutual coupling due to the dense subarray. In accordance with this scheme, we then introduce a symmetric extended transformed nested array (SETNA). A closed-form expression for the proposed array is provided. We also derive the expressions for the DOFs and weights functions of the SETNA. Theoretical analysis, coupled with numerical simulations, reveals that the proposed SETNA adeptly tackles the challenge of Direction of Arrival (DOA) estimation for the localization of mixed-field sources.