TRIPLE TWO-LEVEL NESTED ARRAY WITH IMPROVED DEGREES OF FREEDOM

A triple two-level nested array (TTNA) configuration is proposed for direction-of-arrival (DOA) estimation of multiple time-space signals. The proposed TTNA consists of multiple two-level nested arrays, and the distance between two adjacent nested arrays is also given according to a nested array. As traditional nested arrays, it can generate a hole-free different co-array. Compared with some preexisting nested arrays, the proposed nested array can offer more degrees of freedom (DOFs). The closed-form expression of DOFs and the array configuration are given. Moreover, the detailed process for the construction of extended covariance matrix also is obtained. The simulation results show that the proposed method offers improved performance in the precision of DOA estimation due to the increase of virtual sensors.