Adaptive beam forming algorithm with the near-field nulling weight

Near-field interference is a common problem in far-field location and detection. To suppress near-field interference in a specified area, a far-field adaptive beam forming method with the near-field nulling weight is proposed. The algorithm does far-field beam forming, while suppressing near-field interference with a mock covariance matrix containing a near-field interference sound source. To research the impact of near-field interference suppression on far-field desired main beams, a stationary phase was used. Simulation results proved that the proposed algorithm can efficiently do beam forming in the far-field, and form nulls in the designed near-field area. When the desired direction in the far-field approached the direction of the suppressed area, the array gain of the main beam decreased. The extent of decrease corresponded to the range and direction of the suppressed area. Larger range and closer orientation to the end fire gave more attenuation of array gain.