Beamforming sensitivity of airborne distributed arrays to flight tracking and vehicle dynamics
Beamforming sensitivity of airborne distributed arrays to flight tracking and vehicle dynamics
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机载分布式阵列的波束形成对飞行跟踪和车辆动力学的敏感性
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
E. Arnold
中科院分区：
文献类型：
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作者：
Joseph A. Vincent;E. Arnold
在本文中，我们确定了由间距紧密的飞行轨迹生成的无人机系统（UAS）雷达二维合成阵列对飞行中干扰的波束形成灵敏度。基于计算机的模拟用于评估阵列波束宽度的灵敏度，以及旁瓣电平对飞行航线（天线）数量和飞行路径中阵列扰动的灵敏度。我们使用从一架最近部署到格陵兰用于极地冰盖勘测的小型固定翼无人机收集的飞行数据来评估预期的飞行路径偏差和飞行器姿态。对于圆形分布的飞行路径偏移，发现飞行路径偏差必须保持在工作波长的约2%以内，以实现30分贝的旁瓣电平（SLL）和20度的半功率波束宽度（BW）。对于七个及以上单元的阵列，无论偏移量大小，最大平均旁瓣电平通常在1分贝以内。旁瓣电平对垂直偏差比对水平偏差更敏感，尽管差异很小。对无人机飞行轨迹扰动的分析表明，预计在不到10%的飞行时间内能够实现30分贝旁瓣电平和20度波束宽度的辐射参数（假设是一个9单元阵列且工作频率为14兆赫）。一个模拟的9单元阵列表现出略优的性能，包括优于具有更多单元的阵列。要在95%的飞行时间内满足波束形成参数，将需要2.76兆赫或更低的工作频率；然而，由于其尺寸，将2.76兆赫所需的大型天线集成到小型无人机中是不切实际的。此外，为满足波束形成要求而改变工作频率对于传感应用可能不切实际。因此，在未来的研究中将对相位补偿方法进行研究。
In this paper, we identify the beamforming sensitivity of 2D synthesized arrays for Unmanned Aircraft Systems (UAS) based radars generated from closely spaced flight tracks to in-flight disturbances. Computer-based simulations are used to assess the sensitivity of array beamwidth, and sidelobe level sensitivity to the number of flight-lines (antennas) and the array perturbation in flight path. We assess expected flight path deviations and vehicle attitude using flight data gathered from a small fixed-wing UAS recently deployed to Greenland for polar ice sheet surveys. For circularly distributed flight path offsets, it was found that flight path deviations must be kept within ∼2% of the operating wavelength to achieve 30 dB Sidelobe Level (SLL) and 20-degree half-power beamwidth (BW). For array sizes of seven elements and greater the maximum average SLL was typically within 1 dB regardless of the magnitude of the offset. SLL are more sensitive to vertical deviations than horizontal, though the difference is small. Analysis of the UAS flight-track perturbations reveals that the radiation parameters of 30 dB SLL and 20 degrees BW are expected to be achieved less than 10% of the flight time (when assuming a 9-element array and an operating frequency of 14 MHz). A simulated nine-element array demonstrated slightly improved performance, including over arrays with more elements. To meet the beamforming parameters for 95% of the flight time would require an operating frequency of 2.76 MHz or lower; however, it is impractical to integrate the large antenna required at 2.76 MHz into a small UAS due to its size. In addition, changing the operating frequency to meet beamforming requirements may not be practical for the sensing application. Thus, phase compensation methods will be investigated in future studies.