Wideband Adaptive Beamforming for Mainlobe Interferences Based on Angle-frequency Reciprocity and Covariance Matrix Reconstruction

The conventional wideband adaptive beam-forming method would deteriorate severely when the interferences are present in mainlobe. To overcome this problem, a wideband adaptive beamforming method for mainlobe interferences is proposed based on angle-frequency reciprocity and covariance matrix reconstruction. In the proposed method, the received wideband signals are firstly decomposed into narrow sub-bands. Based on the angle-frequency reciprocity in steering vector, the wideband matrix filter is constructed to estimate the number of mainlobe interferences. Sequentially, the echo data in element space is transformed to that in beam space, and then the beam-space eigen-projection matrix of each sub-band is calculated to suppress the mainlobe interferences. In the following, the array covariance matrix of each sub-band is reconstructed to eliminate the effect of noise perturbation and mainlobe interferences. Finally, the wideband adaptive weight vector is calculated based on the reconstructed covariance matrices. The effectiveness of proposed method is verified by numerical simulations.