The performance of the Capon beamforming sharply decreases against strong directional and large deviation interference. In order to reduce the impact of the abnormal interference, this paper proposes a large degree of freedom null broadening beamforming for non-circular signals. The signal vector is first extended by a uniform linear conjugate array. The covariance matrix of the array is then reconstructed by projection transformation and diagonal loading technique. Finally, the beamforming is constrained by the characteristic subspace of the guide vector matrix, and the analytic expression of the optimal weights of the method is derived. The numerical simulations demonstrate that the proposed null broadening method has the advantages of high degrees of freedom and strong parameter selection robustness.
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