Improvement of DOA estimation accuracy by using sub-arrays

High resolution method for direction of arrival (DOA) estimation using array antenna is studied actively [1]. In almost previous studies, it is assumed that antenna elements have the same directional patterns. However, it is very difficult to make many antenna elements they have just the same directional patterns. Furthermore, the directional patterns are distorted due to mutual coupling between the elements [2]. The estimation accuracy is decayed if the directional patterns are distorted intensively. In this paper, sub-array techniques are proposed to recover the estimation accuracy. An array is divided into plural sub-arrays and DOAs are estimated using respective sub-array. The estimated directions are averaged to obtain a final result. Two types of sub-array techniques, "Partitioned Arrays" and "Shifted Arrays" are examined and the performances of respective types are compared.