Direction-of-arrival estimation in coprime linear array using three uniform linear arrays considering mutual coupling

Nowadays, sparse arrays have been a focus for direction-of-arrival (DOA). The existing arrays can achieve high degree of freedom (DOF) bigger than the number of sensors when using the spatial smoothing methods. However, the small inter-element spacing degrades the DOA estimation accuracy when facing severe mutual coupling. In order to alleviate mutual coupling, a coprime linear array using three uniform linear arrays (CLA-U3) is proposed. The expression of sensor locations is given, and the analysis of DOF is considered. The minimum subarray inter-element spacing in CLA-U3 is bigger than that of the existing arrays, which means that CLA-U3 can be less sensitive to mutual coupling. Moreover, the difference co-subarrays can fill each other's holes, so CLA-U3 and other sparse arrays composed of three subarrays have close DOF. Simulation experiments prove the favourable performance of DOA estimation.