This paper presents the results of investigations on the beamforming of a low-frequency radio-telescope LOFAR which can be used as a receiver in passive coherent location (PCL) radars for aerial and space object detection and tracking. The use of a LOFAR radio-telescope for the passive tracking of space objects can be a highly cost-effective solution due to the fact that most of the necessary equipment needed for passive radiolocation already exists in the form of LOFAR stations. The capability of the radiolocation of planes by a single LOFAR station in Borowiec is considered to be `proof of concept’ for future research focused on the localization of space objects. Beam patterns of single sets of LOFAR antennas (known as tiles), as well as for the entire LOFAR station, are presented and thoroughly discussed in the paper. Issues related to grating lobes in LOFAR beam patterns are also highlighted. A beamforming algorithm used for passive radiolocation purposes, exploiting data collected by a LOFAR station, is also discussed. The results of preliminary experiments carried out with real signals collected by the LOFAR station in Borowiec, Poland confirm that the appropriate beamforming can significantly increase the radar’s detection range, as well as the detection’s certainty.

中文翻译：

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LOFAR射电望远镜的波束赋形，用于无源无线电定位

本文介绍了对低频无线电望远镜LOFAR波束形成的研究结果，该低频无线电望远镜可以用作无源相干定位（PCL）雷达的接收器，用于航空和空间物体的检测和跟踪。由于无源无线电定位所需的大多数必要设备已经以LOFAR台站的形式存在，因此使用LOFAR射电望远镜进行空间物体的被动跟踪可能是一种极具成本效益的解决方案。Borowiec的单个LOFAR站对飞机进行无线电定位的能力被认为是“概念证明”，对于未来针对空间物体定位的研究而言。本文介绍了单组LOFAR天线（称为磁贴）以及整个LOFAR站的波束方向图。还突出显示了与LOFAR光束方向图中的光栅波瓣有关的问题。还讨论了用于无源无线电定位目的的波束成形算法，该算法利用了LOFAR站收集的数据。由波兰Borowiec的LOFAR站收集的真实信号进行的初步实验结果证实，适当的波束成形可以显着增加雷达的探测范围以及探测的确定性。