【摘要】 相控阵雷达同时多波束成像可广泛应用于环境检测、弹载平台定位等场合.文中根据相控阵原理设计了同时多波束天线方向图,推导了方向图各波束指向、波束宽度与阵列结构参数的关系.在对各波束回波信号特性分析的基础上,得到了宽带条件下不同应用环境时多普勒谱不混叠条件,推导了多波束成像模式对脉冲重复频率的约束条件.在合理参数的情况下,获得总的回波信号并通过对应于各波束的频域滤波器分离各波束回波信号,利用方位向上的非线性调频变标算法分别进行SAR成像,并对各波束成像性能进行了分析.仿真结果表明,本文模式可实现同时多波束成像,当平台速度与阵列法线垂直时,SAR斜视角不大的情况下,各波束SAR图像方位分辨率基本保持不变;当平台速度与阵列法线重合时,各波束SAR成像方位分辨率随波束指向靠近法线分辨率急剧下降,但远离法线又会带来更严重的孔径渡越效应,因此应合理确定SAR成像各波束指向.更多还原

【Abstract】 Phased array radar based simultaneous multi-beams can be used in many fields for activities for change detection and platform location. This paper proposes a method for multi-beam antenna pattern design based on the phased array radar principle. In the proposed method, the relationships between the array structure, the direction and the width of the beams are deduced. Based on analysis of echo characters, the limiting conditions in various applications are obtained to ensure that the spectrums from different beams are not aliasing.Using the designed antenna pattern and parameters, echoes from different beams are received and separated by filtering the signal using a bank of filters corresponding to each beam. After separation, an azimuth nonlinear chirp scaling method is applied to the echoes of each beam for imaging and the imaging performance is analyzed.Simulation results show that the mode is efficient. The results also demonstrate that(1) when the platform velocity is perpendicular to the array normal line and the squint angle is not sufficiently large, the azimuth resolution is kept constant;(2) when the platform velocity is parallel to the normal line, the azimuth resolution declines sharply if the beam direction gets close to the normal line. However, if the beam direction deviates from the line,the effects of the antenna fill time becomes serious; therefore, an appropriate beam direction should be chosen.更多还原