Robust Adaptive Beamforming of LFM Signals Based on Interference-plus-Noise Covariance Matrix Reconstruction in Fractional Fourier Domain

The linear frequency modulation (LFM) signal can accumulate as an impulse by the fractional Fourier transform (FRFT), and the phase differences among the peaks on the sensors mainly depend on the direction of arrival of the LFM signal and the antenna structure. A novel robust adaptive beamforming is proposed by the interference-plus-noise covariance matrix (INCM) reconstruction in fractional Fourier domain. The FRFT is applied to the radar echoes and then the peaks can be extracted to reconstruct the INCM with the Capon spatial spectrum. The optimal weight vector can be obtained by solving the optimization problem. Simulation results demonstrate that the proposed method can efficiently suppress the deception interferences of false targets, and outperform other tested beamformers across a wide range of signal-to-noise ratios.