中文摘要：

波束形成中波束图的主波束宽度和旁瓣级是最重要又相互矛盾的一对指标。直线阵在端射方向具有超增益现象，能够获得比常规波束窄得多的波束。而Dolph—Chebyshev等人提出的阵元幅度加权理论可以使得在主波束宽度一定的情况下获得最低的旁瓣级。本文结合两者的优点，提出了一种基于声压梯度分析的小间隔直线阵端射方向波束形成方法。该方法通过均匀直线阵的阵列流形提取出阵列中心点处的各阶声压梯度模态，然后在模态域进行Dolph．Chebyshev（Dc）加权，再把模态域权值变换成阵元域权值。针对阵元间距小于半波长的直线阵进行了计算机仿真，仿真结果表明，该方法得到的波束图主瓣宽度远小于相同旁瓣级的常规DC加权波束图，有效提高了波束空间处理增益。

英文摘要：

The main lobe width and side lobe level of beampattern are two most important performance measures in beamforming. Super-directivity beamforming method can gain a narrower main lobe compared with conventional beams at end-fire direction for small interelement space uniform linear arrays（ ULAs）, and the Dolph-Chebyshev（DC） amplitude weighting method can obtain the lowest side lobe level at specific main lobe width. A new bearaforming method at end-fire direction for smaU aperture linear arrays based on acoustic pressure gradient analysis is proposed in this paper. The method combines the super-directivity theory and DC weighting method. The mode-filter matrix is used to extract higher order modes of pressure gradients at array center from the array manifold. The end-fire beam pattern is synthesized with DC weights in mode domain, and then the beam forming weights are transformed into element domain. Compared with the common DC weighted beam forming, this new approach can obtain bet- ter performance at end-fire direction. Simulation results show that this method is effective.