Electrically Small Antennas as Probe for UAV-Based Antenna Measurements

Uninhabitated Aerial Vehicles (UAVs) are increasingly used in antenna measurements and testing, where in particular one or more receiving probes may be carried by the UAV to evaluate the performance of antennas or radio systems in real-world scenarios. Utilizing electrically small probing antennas offers the advantages of extended flight duration and reduced overall UAV weight, especially for low frequencies. In this study, we investigate the performance of the receiver when employing small loops or dipoles as probes. Additionally, we derive a comprehensive expression for the signal-to-noise ratio (SNR) and the system noise figure, which accounts for factors such as ohmic loss and mismatch loss, aspects that are often ignored when calculating the equivalent noise temperature of an antenna.