A horizontal planar scanner with an approximate size of 40 m $\times40$ m has been implemented using the Unmanned Aerial Vehicle (UAV) technology. The UAV is not wired to the ground to maintain the flexibility and short setup time of a non-tethered flight. In this configuration, the UAV-mounted continuous-wave source is not phase-locked to the on-the-ground receiver. A dual-polarized reference antenna placed on the ground is hence used to retrieve the relevant phase information. The presented approach has been applied on the Pre - Aperture Array Verification System (Pre -AAVS1) of the Square Kilometre Array, which is a digital beamformed array with 16 active elements. An inverse source technique has been applied on measured Near-Field (NF) data acquired on two different sets of points (one for each electric field component) from all the receiver channels. In this way, Embedded Element Patterns (EEPs), array calibration coefficients and pattern have been determined from NF data only. The achieved results have been validated using a complementary set of Far-Field (FF) measurements and simulations.

中文翻译：

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基于非系留无人机的大型水平近场扫描仪

大约 40 m 大小的水平平面扫描仪 $\times40$m 已使用无人驾驶飞行器 (UAV) 技术实施。无人机没有连接到地面，以保持非系留飞行的灵活性和较短的设置时间。在这种配置中，安装在无人机上的连续波源不会与地面接收器锁相。因此，使用放置在地面上的双极化参考天线来检索相关的相位信息。所提出的方法已应用于平方公里阵列的预孔径阵列验证系统 (Pre-AAVS1)，该阵列是具有 16 个有源元件的数字波束形成阵列。逆源技术已应用于测量的近场 (NF) 数据，该数据是从所有接收器通道的两组不同点（一个用于每个电场分量）上采集的。通过这种方式，嵌入式元素模式 (EEP)，阵列校准系数和模式仅由 NF 数据确定。已使用一组互补的远场 (FF) 测量和模拟验证了所取得的结果。