Beamforming technique based on nonuniform signal recovering algorithm in multi-carrier frequency MIMO HF radar

In order to boost HF radar angle resolution and reduce the physical size of array, we adopt multi-carrier frequency in MIMO HFSWR system, which also lead to the benefit of the frequency diversity. Beamforming at receive array is studied in this paper, and thanks to the using of large spaced carrier frequency combination, better angle resolution is obtained by a nonuniform virtual array (a minimally redundant array) with extended aperture than the physical real array, but high slop lobe appears as a drawback. For the purpose of suppressing the slop lobe, a nonuniform signal recovering algorithm based on sparseness-constrained least-squares inversion is proposed in recovering uniform sampling signal, after which the recovered signal is used to beamfoming. Simulation results demonstrate that slop lobe is suppressed successfully.