High-Resolution 5G Active Antenna Beam Pattern Measurement Using UAVs

This paper presents a measurement methodology for obtaining a high-resolution beam pattern of 5G active antenna systems (AASs) using Unmanned Aerial Vehicles (UAVs). Beam pattern measurements are typically conducted in an anechoic chamber by placing the active antenna at the center and radiation pattern is measured at various angles. This approach is limited by the spatial constraints of the chamber and is time-consuming for obtaining high-resolution measurements. To address this problem, UAVs equipped with measurement sensors are proposed to fly around the antenna and do the measurement campaign. The beam pattern measurement campaign problem is formulated into a UAV path planning problem. Horizontal circular arcs at various elevation angles are defined on a sphere centered at the antenna and connected at their ends alternatively to define a reference path and transcribe it into a reference trajectory for the UAV. A chattering-free super-twisting controller is designed to accurately track this trajectory against unknown matched disturbances and model uncertainties. The proposed methodology is validated by an indoor experiment with a horn antenna set up to operate in the frequency range of a 5G AAS and create a stationary beam. A universal software radio peripheral is mounted on a UAV and programmed to measure the received signal strength indicator in real time and a high-resolution beam pattern is satisfactorily captured.