This thesis proposes to characterize antennas in situ with Unmanned Aerial Vehicles (UAVs), especially within the framework of weather radar and 5th generation wireless systems (5G) antennas. Specifically, it is concerned with devising the requirements and tradeoffs of such a system. Characterizing an antenna in its operational environment is important to ensure that it meets its performance requirements, once it is installed in a larger system. Several techniques exist to carry out this task. Balloon-tethered dipoles at different heights were used to measure antennas radiation patterns in elevation as early as 1965. In 1988, helicopters replaced balloons and permitted the measurement of any antenna radiation pattern cut. In 2014, UAVs emerged to carry out this task for VHF and UHF antennas only, pointing at zenith, and with low directivity. However, measuring high-gain antennas pointing at low elevation angles presents more challenges, which this thesis takes into account.
First, requirements for weather radar systems as well as 5G base station antennas are listed, as well as general measurement requirements, including phase, amplitude, ground reflection, and link budget requirements. Then, the requirements and tradeoffs for characterizing antennas using UAVs are presented. The different scanning strategies are exposed, as well as the necessary distance for measuring antenna pattern cuts. The effect of ground reflections on the measurements is set forth. The positioning accuracy of a UAV platform, specifically of its Global Positioning System (GPS), Inertial Measurement Units (IMUs), and gimbal, is presented, with a focus on the in-house Advanced Radar Research Center (ARRC) hexacopter. The effects of the UAV position and gimbal drifts on the measurements are formulated theoretically, and illustrated. Two radiating structures to be mounted on the UAV are studied---a 3x3 and a 2x2 dual-polarized patch antenna arrays, with different UAV platforms---the in-house ARRC hexacopter and octocopter as well as the DJI Phantom 3. Following is a presentation of the design process of a UAV platform, with an emphasis on the required performance factors pertaining to in situ antenna characterization. Finally, a proof of concept of this system is shown, using a commercially available UAV---DJI Phantom 3---equipped with a quarter wavelength monopole antenna that measures a custom traveling wave antenna
