3-D ambiguity analysis method of arbitrary antenna array for direction finding

In this paper we propose an approach to 3-D ambiguity (type I ambiguity [l]) analysis of arbitrary antenna arrays. Ambiguity characterization is very important in designing antenna array for direction finding in mobile communications/indoor positioning/radar, which greatly influences practical capability of Direction of Arrival (DOA) estimation. Conventional 2-D ambiguity analysis loses most of ambiguity information in 3-D space and cannot indicate ambiguity from 3-D space out of the selected 2-D plane; Cramér-Rao bound (CRB) analysis outputs unidentified pattern when real measured data exhibits less regular behavior than ideal data, moreover it only provides variance low bound instead of exact value or upper bound. We defined and proposed the 3-D ambiguity analysis with full 3-D ambiguity information of antenna array, and shows (by real measured data) that proposed method is a plain and utility tool for ambiguity characterization suitable for practically designing arbitrary antenna arrays.