This paper presents a comprehensive survey of state-of-the-art UAV–based antennas and propagation measurements. Unmanned aerial vehicles (UAVs) have emerged as powerful tools for in situ electromagnetic field assessments due to their flexibility, cost-effectiveness, and ability to operate in challenging environments. This paper highlights various UAV applications, from testing large–scale antenna arrays, such as those used in the square kilometer array (SKA), to evaluating channel models for 5G/6G networks. Additionally, the review discusses technical challenges, such as positioning accuracy and antenna alignment, and it provides insights into the latest advancements in portable measurement systems and antenna designs tailored for UAV use. During the UAV–based antenna measurements, key contributors to the relatively small inaccuracies of around 0.5 to 1 dB are identified. In addition to factors such as GPS positioning errors and UAV vibrations, ground reflections can significantly contribute to inaccuracies, leading to variations in the measured radiation patterns of the antenna. By minimizing ground reflections during UAV–based antenna measurements, errors in key measured antenna parameters, such as HPBW, realized gain, and the front-to-back ratio, can be effectively mitigated. To understand the source of propagation losses in a UAV to ground link, simulations were conducted in CST. These simulations identified scattering effects caused by surrounding buildings. Additionally, by simulating a UAV with a horn antenna, potential sources of electromagnetic coupling between the antenna and the UAV body were detected. The survey concludes by identifying key areas for future research and emphasizing the potential of UAVs to revolutionize antenna and propagation measurement practices to avoid the inaccuracies of the antenna parameters measured by the UAV.

Wireless systems have been upgraded over the past several years and as a result, drone-based communications have found a wide range of applications. This paper presents the performance of a printed log-periodic antenna, which operates in the frequency range from 0.7 to 6.5 GHz when mounted on the top of a drone. The effect of a metallic mast and a base plate is considered in our analysis. From our simulations, it is observed that an improvement in realized gain of 1.6 dB is obtained over a frequency band of 2 to 6.5 GHz. All simulations are performed using CST Studio Suite.

A dual-pattern reconfigurable antenna comprising a torus-shaped metasurface controlled by flip-chip Aluminum Gallium Arsenide (AlGaAs) PIN diodes and a bicone antenna feed is investigated. A broadband bicone antenna operating between 14 and 34 GHz is initially optimized to enhance its realized gain and achieve 4.1 dBi at 29 GHz and 4.4 dBi at 30 GHz. The designed bicone is subsequently used as a feed for the torus-shaped metasurface. A torus-shaped metasurface capable of switching between reflection and transmission is investigated in two stages. Its geometry is optimized as a metallic reflector to reduce computational time. The dimensions of the reflector are optimized to improve the gains and lower the side lobe levels (SLL). The simulation of the reflector confirms that the torus reflector with the bicone feed achieves a realized gain of 16.3 dBi at 29 GHz and 17 dBi at 30 GHz. The proposed metasurface achieves transmission and reflection switching between 27.5 and 30.5 GHz by controlling the PIN diode state. Based on the results, the proposed system can operate in two distinct modes: omnidirectional and directional. The expected omnidirectional performance of the final system corresponds to that of the standalone bicone antenna, reduced by the metasurface insertion loss. In the directional mode, the realized gain and radiation pattern are determined by the combined response of the bicone antenna and torus-shaped metasurface reflector.

A Gregorian Dual Reflector configuration is proposed to scan an area ranging from -1.2° to 1.2°. The proposed configuration consists of a paraboloidal main reflector, elliptical sub-reflector operating at Ku-Band and sharing common feed point. Imaging arrangement is obtained by translation, rotation and focal length adjustment of the feed. An attractive feature of the imaging arrangement is that they are capable to scan one beam electronically and generate multi beam coverage in a limited field of view. As an application, a 0.6m diameter main reflector with a cluster of WR-51 waveguides is utilized to get an H.P.B.W of 1.8°.

A dual function metasurface based on flip-chip Aluminium Gallium Arsenide (AlGaAs) PIN diodes is presented. Depending on the biasing state of the PIN diodes, the metasurface exhibits either a 1-bit reflection response or a transmission response. The design was optimized using the full 3D model of the AlGaAs PIN diodes. Simulations have been carried out using CST microwave studio to evaluate the performance of the dual function metasurface. The optimized metasurface demonstrates an average reflection loss of 0.3 dB and a transmission loss of 1.09 dB at 29 GHz. The corresponding simulation results were compared against both the simulated (obtained from a SPICE model developed in a circuit simulator) and measured S-parameters of the diodes. The transmission and reflection responses obtained at the operating frequency remain consistent across the three modelling approaches are presented and discussed.