Investigation of the measurement distance for an UAV-performed radiation pattern measurement

The transmission of radio signals in a very high frequency band (30–300 MHz) is facilitated by large antenna systems situated at high altitudes and significant heights above the ground. Measuring the radiation pattern is crucial for determining the functionality of these systems, particularly before and after replacing old antennas with new ones. This study focuses on analysing amplitude errors caused by the quadratic phase error resulting from wavefront curvature in finite-distance radiation pattern measurements. The article presents horizontal and vertical radiation patterns of antenna systems of different sizes and topologies, calculated using the computational software Altair FEKO. Deviations from the radiation patterns calculated for the ideal case of infinite distance are discussed. Additionally, the calculated vertical radiation patterns are compared to those obtained from measurements performed by the commercially available DJI Matrice 300 quadcopter and a specialized measurement device.