Robust wideband adaptive beamforming with null broadening and constant beamwidth

In the cases of rapidly moving interference and look-direction error, robustness and output signal to interference and noise ratio (SINR) of conventional wideband adaptive beamforming methods are degraded severely. In order to solve these problems, a robust wideband adaptive beamforming with null broadening and constant beamwidth is proposed. We first propose a taper matrix constructed by adding virtual interferences for null broadening, where the reference frequency and number of virtual interferences of taper matrix are determined based on numerical methods. This is followed by reconstructing the array covariance matrix based on taper matrix. Spatial response variation (SRV) constraint is then applied for a constant beamwidth over the entire frequency band. Finally, the adaptive weight vector for null broadening and constant beamwidth is obtained by using Lagrange multiplier method. The effectiveness of proposed method is verified by numerical simulations.