In order to enlarge the array aperture in the case of having determinate number of sensors

this paper utilizes a sparse symmetric array which allows the inter-element spacing to exceed the quarter-wavelength upper limit.To avoid the direction-of-arrival (DOA) ambiguity and complicated 2-D search

a method based on rank reduction(RARE) has been presented for estimating the DOA and range of near-field sources without ambiguity.And the ambiguity of DOA estimation is analyzed.The algorithm utilizes second-order statistics and only requires 1-D search

and all parameters are automatically matched.Therefore the computational burden is reduced and the spatial resolution is enhanced when the number of sensors is limited.Simulations are included to show the validity of this proposed method.