Robust wideband beamforming method for linear frequency modulation signals based on digital dechirp processing

This study presents a robust digital beamforming (DBF) method for wideband digital array radar, which uses linear frequency modulation (LFM) waveforms. Firstly, received signals are digitally dechirped, followed by narrowband filtering and decimation. Then the authors generate time-variant factors to compensate phase perturbations induced by the dechirp processing. It is proved that the wideband LFM signals can be treated as narrowband signals after compensation. Finally, a robust adaptive narrowband DBF method based on uncertain set constraints and interference-plus-noise matrix reconstruction is applied to suppress the interferences. The proposed method is computationally efficient and feasible for real-time applications. It behaves robustly in the presence of direction of arrival estimation errors across a wide range of signal-to-noise ratios. Simulations demonstrate the effectiveness and feasibility of the proposed method.