A COVARIANCE APPROXIMATION METHOD FOR NEAR-FIELD DIRECTION-FINDING USING A UNIFORM LINEAR-ARRAY

Most narrowband high-resolution bearing estimation algorithms were proposed based on the assumption of a far-field source environment, When this assumption is violated, i.e., some sources are in the near field, these algorithms generally provide unsatisfactory performances. In this correspondence, a new algorithm is proposed to handle this near-field problem using a uniform linear array. The received signal covariance matrix for near-field sources is viewed as a corrupted measurement of the ideal signal covariance matrix for far-field sources located at the same bearings, Taking this viewpoint, we reconstruct a far-field approximation (FFA) covariance matrix from the received covariance matrix to reduce the corruptions, Therefore, existing high-resolution bearing estimation techniques can be directly applied to estimate the bearings of the near-field sources, The properties of the proposed approach are investigated in detail, Simulation results demonstrating the effectiveness of this approach are included.