A pentad-displaced ULAs configuration with hole-free co-array and increased degrees of freedom for direction of arrival estimation

Abstract

In the recent past, sparse arrays have received significant attention due to their inherent ability of offering increased degrees of freedom (DOFs) along with an enlarged array aperture, compared to uniform linear arrays (ULAs). These attributes are essential to improve the direction-of-arrival (DOA) estimation accuracy. Keeping in view, a new sparse array configuration based on pentad-displaced ULAs (Pdis-ULAs) structure is presented in this paper. The proposed geometry generally consists of five ULAs and a single element placed effectively. Both the intra-ULA sensor placement and the displacement between ULAs, are uniquely determined by analytical expressions. The configuration is also benefited with closed-form expression to calculate the number of DOFs. Compared to the existing sparse array designs, the proposed configuration achieves more DOFs and wider array aperture for a given number of sensors. Moreover, the Pdis-ULAs structure desirably produces a hole-free resulting co-array. Owing to these improvements, the proposed antenna array scheme can accurately resolve the DOAs of several sources and achieves superior DOA estimation performance in under-determined conditions. Numerical works are carried out to validate the effectiveness of the Pdis-ULAs configuration.