Adaptive beamforming of digital array radar in the presence of near-field

Due to the non-uniformity of the wave-front in the presence of near-field, the performance of the adaptive beamforming algorithm has suffered degradation. On the analysis of the multi-channel radar returning signal mode and frequency spectrum in the presence of near-field, an interesting phenomenon has been found that the spectrum of the near-field return signal undergo distortion—“chromatic dispersion” resulting from the frequency variation. Furthermore, the interference sample selection would be so insufficient that the completed sample covariance matrix does induce the inhomogeneous spectrum partition, resulting in the effectiveness of the adaptive digital beamforming (ADBF) algorithm. Based on the characteristic of special spectrum, a new near-field ADBF (NF-ADBF) algorithm is proposed with different sample division strategy and hierarchical threshold set in the grid region to increase the corrosion property of adaptive processing. Through constructing ground simulation test environment to accomplish data acquisition, the proposed NF-ADBF method and novel sample recombination tactics are proved.