DOA Estimation for Mixed Circular and Noncircular Signals by Using the Conversion Relationship Between URAs and a Virtual ULA

In this letter, a two-dimensional (2-D) DOA estimation method based on rank reduction (RARE) for hybrid circular and noncircular signals is proposed. In the case of coexistence of circular and noncircular signals, the method first transforms the uniform rectangular arrays to a virtual uniform linear array. Multiple 2-D DOAs are then decoupled into several 1-D DOAs using RARE method. Compared with the existing MUSIC-like methods, the proposed method utilizes noncircularity feature to improve angle estimation performance. Theoretical analysis and simulation results verify the effectiveness of the proposed method, which has superior estimation performance than the existing methods in terms of low signal-to-noise ratio.