Bistatic MIMO radar for exact near-field target localization with COLD arrays

Abstract

Most existing near-field target localization algorithms are based on the Fresnel approximation model, which can lead to a decrease in parameter estimation accuracy. In this paper, we combine bistatic multiple-input multiple-output (MIMO) radar with concentered orthogonal loop and dipole (COLD) arrays to propose a six-dimensional (6-D) parameter estimation algorithm based on an exact near-field spatial propagation geometry model. The proposed algorithm first performs eigenvalue decomposition of the covariance matrix of the receiving array and utilizes the rotational invariance technique to obtain estimates of two-dimensional reception polarization angles (2D-RPA). Then, the unambiguous spatial amplitude attenuation factors and ambiguous spatial phase factors are estimated. Two overdetermined linear equations are constructed and solved with the estimated spatial amplitude attenuation factors to obtain coarse direction of departure (DOD), range from transmitter to target (RFTT), direction of arrival (DOA), and range from target to receiver (RFTR) estimation. Finally, the coarse estimates of DOD, RFTT, DOA, and RFTR are combined with the estimated ambiguous spatial phase factors to obtain the unambiguous spatial phase factors, thereby achieving fine estimation of DOD, RFTT, DOA, and RFTR. The proposed algorithm achieves automatically matching of 6-D parameters that is superior to exiting method, simulation results validate its effectiveness.