Unmanned Aerial Vehicles (UAVs) offer promising potential as communications node carriers, providing on-demand wireless connectivity to users. While existing literature presents various channel models, they often overlook the impact of UAV heading. This paper experimentally characterizes Air-to-Ground (A2G) and Ground-to-Air (G2A) wireless channels in obstacle-free, interference-free open environments, accounting for distance and UAV heading. We analyze the Received Signal Strength Indicator (RSSI) and TCP throughput between ground users and UAVs, covering distances between 50 m and 500 m, and considering different UAV headings. Our study offers a more accurate channel model characterization compared to deterministic models such as Friis and two-ray. Additionally, we characterize the antenna's radiation pattern based on UAV headings.

翻译：无人机作为通信节点载体具有巨大潜力，可为用户提供按需无线连接能力。现有文献虽提出了多种信道模型，但往往忽略了无人机航向的影响。本文在无遮挡、无干扰的开放环境中，通过实验表征了考虑距离与无人机航向的空对地（A2G）与地对空（G2A）无线信道特性。我们分析了地面用户与无人机之间在50米至500米距离范围内不同航向下的接收信号强度指示（RSSI）和TCP吞吐量。相较于Friis和双射线等确定性模型，本研究提供了更精确的信道模型表征。此外，我们还根据无人机航向表征了天线辐射方向图。