旋翼无人机调频连续波雷达滑轨成像及特性分析

对旋翼无人机的精细化特性分析是提高雷达对“低慢小”目标分类和识别能力的关键。从目标距离-方位二维雷达成像的角度出发,利用K波段和太赫兹两个波段的调频连续波（FMCW）雷达,实现对旋翼无人机目标的滑轨成像。首先,建立了雷达滑轨成像的信号处理模型,给出了回波距离-方位二维聚焦的实现方法。其次,从雷达波段、调制带宽、扫频周期、滑轨长度、成像时间等多个角度分析和比较雷达成像性能的影响因素。最后,选取三种不同尺寸的典型旋翼无人机,利用两个波段FMCW雷达开展成像实验。实测数据分析表明:无人机在静止状态下,成像散射点能够较为精确地反映目标的物理结构;悬停状态受旋翼转动的影响,回波幅度增强,在距离和方位向能量发散程度与叶片长度和转速有关,并表现明显的微动特性,利用旋翼对无人机主体运动的调制和扰动特性,可用于后续的目标分类和识别。 

Slide Imaging and Characteristics Analysis of Rotary-wing Drone Using Frequency Modulated Continuous Wave Radar

? ?The refined characteristics analysis of the rotary-wing drone is the key point to improve the radar's ability for "low, slow and small" target classification. From the perspective of range-azimuth two-dimensional radar imaging, two bands frequency modulated continuous wave radar （FMCW）, i.e., the K-band and terahertz band, are used to realize the sliding imaging of the rotor drone. Firstly, the signal processing model of radar slide imaging is established, and the realization method of range-azimuth two-dimensional focusing is given. Secondly, the influencing factors of radar imaging performance are analyzed and compared from multiple angles such as radar band, modulation bandwidth, modulation period, slide rail length, imaging time. Finally, three typical rotary wing drones of different sizes were selected to carry out imaging experiments using the two-bands FMCW radars. Analysis of measured data shows that when the drone is at rest, the imaging scattering point can accurately reflect the physical structure of the target; the hovering state is affected by the rotation of the rotor, the echo amplitude is enhanced, and the energy divergence in the distance and azimuth happens, which is related to the blade length and the rotation speed. At this time, micro-motion shows characteristics become more obvious. The properties of the rotor modulation and disturbance on the drone body can be used for subsequent target classification and recognition.