近场干扰是影响远场定位和检测的常见问题。为了抑制确定区域的近场干扰,提出了一种具有近场零陷权的远场自适应波束形成的设计方法。算法通过构造包含近场干扰源的虚拟协方差矩阵,实现了具有近场干扰抑制能力的远场波束形成,并应用驻定相位原理,分析了近场干扰抑制对于远场期望方向波束的影响。仿真实验证明:该算法可实现远场波束形成的同时,在近场设计区域生成有效的零陷;当期望方向趋近零陷区域方位时,主波束的阵增益会下降,零陷区域方位愈靠近阵列端射方向、零陷区域距参考阵元的距离愈大,阵增益下降程度愈剧烈。
Near-field interference is a common problem in far-field location and detection. To suppress near-field in- terference 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 suppres- sion 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.