The issue of asset tracking in dense environments where the performance of the global positioning system (GPS) becomes unavailable or unreliable is addressed. The proposed solution uses a low-profile array of antenna elements (sensors) mounted on a finite conducting ground. A compact-size sensor array of six electrically small dual-band omnidirectional spiral antenna elements was designed as a front end of a tracker to operate in the 402 and 837 MHz spectrum bands. For the lower band, a three-element superposition method is applied to support estimation of the angle of arrival (AOA), whereas all six sensors are employed for the higher band. A low complexity and accurate AOA determination algorithm is proposed, the projection vector (PV), and this is combined with the array mentioned. Orthogonal frequency division multiplexing (OFDM) is integrated with the PV technique to increase the estimation resolution. The system was found to be suitable for installation on the roof of vehicles to localize the position of assets. The proposed system was tested for the tracking of nonstationary sources, and then two scenarios were investigated using propagation modeling software: outdoor to outdoor and outdoor to indoor. The results confirm that the proposed tracking system works efficiently with a single snapshot.

中文翻译：

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使用双波段传感器阵列的车辆跟踪系统的 AOA 定位

解决了全球定位系统 (GPS) 性能变得不可用或不可靠的密集环境中的资产跟踪问题。提议的解决方案使用安装在有限导电地面上的低剖面天线元件（传感器）阵列。一个由六个电子小型双频段全向螺旋天线元件组成的紧凑型传感器阵列被设计为跟踪器的前端，以在 402 和 837 MHz 频段中运行。对于较低频段，应用三元素叠加方法来支持到达角 (AOA) 的估计，而所有六个传感器都用于较高频段。提出了一种低复杂度和精确的AOA确定算法，投影向量（PV），并将其与上述阵列相结合。正交频分复用 (OFDM) 与 PV 技术相结合以提高估计分辨率。该系统被发现适合安装在车辆的车顶上，以定位资产的位置。对所提出的系统进行了非平稳源跟踪测试，然后使用传播建模软件研究了两种情况：室外到室外和室外到室内。结果证实，所提出的跟踪系统可以有效地处理单个快照。室外到室外和室外到室内。结果证实，所提出的跟踪系统可以有效地处理单个快照。室外到室外和室外到室内。结果证实，所提出的跟踪系统可以有效地处理单个快照。