弯曲阵面机载共形阵列雷达方向图与杂波相关性研究

Research on The Relation between the Beampattern and Clutter Distribution of Curved Surface Array for Airborne Conformal Array Radar

针对载体弯曲效应对机载共形阵列雷达方向图和杂波特性的影响,该文在正侧视条件下评估均匀圆环阵方向图性能,分析不同位置阵元对弯曲阵面方向图合成效率的影响,发现边缘阵子不仅对共形阵列方向图主瓣增益贡献较小,反而更易引起旁瓣抬升等挑战,降低共形阵的孔径利用效率。另一方面,通过严格的理论推导完成共形阵列雷达方向图特性与杂波扩展效应内在物理联系的分析,发现弯曲阵面引起的方向图非理想畸变是共形阵杂波非均匀扩展的核心影响因素。在此基础上,进一步分析共形雷达单个贴片微带阵元加工和安装结构组件将增大阵元物理尺寸,使得共形阵列雷达相邻阵元间距大于半波长,当阵元间隔增大到一定程度时,在方向图远区会形成较高的栅瓣,进一步影响机载共形阵列雷达的杂波分布,通过仿真分析发现在特定的脉冲重复频率(PRF)条件下,“栅瓣杂波”折叠进入主瓣杂波,该文提出通过优化雷达PRF设计,避免栅瓣杂波的折叠效应对机载共形阵列雷达信号处理性能的影响,相关仿真结果验证了所提方法的有效性。

To demonstrate the performance of beam-pattern and clutter distribution for airborne conformal radar due to the bending effect of carrier,the half-uniform circular array and fan-shaped array with the same radius are compared in the array synthesis characteristic,in the case of vertical side-looking.It is found that the edge elements have little contribution on the main-beam gain,alternatively,but enhances the side-lobe level so obvious that the combination property of the radar and aperture efficiency suffers degradation.Simultaneously,the inherent relation between the beam-pattern and the clutter spread is proved that the beam distortion resulting from the curved surface is the core factor on the clutter distribution inhomogeneity,through strict theoretical reduction.On the basis of the previous discussion,the additional structure of manufacture and installation,which would increase the physical dimension,is considered to enlarge the space between the adjacent radiators.In particular,the grating-lobe has appeared on the far-field pattern and made further efforts on the clutter distribution for Conformal Array Radar(CAR),in the condition of the reasonable element interval.One to be noted is that the grating-lobe clutter is folded to the main-lobe clutter region under the specific Pulse Repetition Frequency(PRF).To avoid the foldover of clutter,the PRF of CAR can be optimized and the related simulation is conducted to verify the effectiveness of the proposed method.