A UNITARY TRANSFORMATION METHOD FOR ANGLE-OF-ARRIVAL ESTIMATION

Eigenstructure methods for estimating angles of arrival of radiation sources generally require complex computations in computing eigencomponents of the covariance matrix and calculating the search function. In this correspondence, we present a unitary transformation method which transforms the complex covariance matrix of an equally spaced linear array, which is Hermitian persymmetric, and the complex search vector into a real symmetric matrix and a real vector, respectively. Therefore, both tasks can be accomplished by real computations. Practically, the sampled covariance matrix available is not persymmetric. To suit the unitary transformation method, we propose a persymmetrized estimator of the sampled covariance matrix, which is optimal in the sense of Euclidean distance.