On reconfigurable antennas in unmanned aerial vehicles

Unmanned aerial vehicles (UAVs), also known as drones, have gained significant attention in recent years due to a wide range of military as well as civilian applications. Due to high mobility, flying at different altitudes and in different environments, their design, structure, size, weight, connectivity, coverage, communication, and various other factors are of critical importance. UAV communication systems should be able to incorporate seamless connectivity, wide coverage, high-quality signal, and operation over a wide range of frequencies. Thus, antennas are critical to enhance received signal quality and to extend UAV coverage. Reconfigurable Intelligent Surfaces (RISs) and antennas have drawn significant attention recently due to their enormous potential in wireless communication systems and have been widely studied for UAVs too. This paper presents a comprehensive survey of reconfigurable intelligent surfaces and antennas and their deployment in UAVs. It also presents a critical analysis and evaluation of the research work conducted on reconfigurable antennas in UAVs. Challenges and future research directions have also been presented. Lastly, some significant UAV applications and prospects of UAV-based communication combined with modern technologies have been discussed.