Vol.:(0123456789) 1 3 Telecommunication Systems https://doi.org/10.1007/s11235-019-00640-1 UAVs-based antenna arrays using time modulation Diana A. Jiménez 1  · Alberto Reyna 1,2  · Marco A. Panduro 3  · Carlos del Rio 4  · Gopi Ram 5  · Luz Balderas 1 © Springer Science+Business Media, LLC, part of Springer Nature 2019 Abstract This paper applies time modulation to deal with the design of antenna arrays for UAVs formation fight using a rectangular micro-strip as antenna element in the frequency of 2.4 GHz. The motivation for this paper is to exploit the properties and advantages of time-modulated arrays in an interesting application: UAVs formation fight. This design considers the opti- mization of the position of the drones (or antenna elements) and the time switched sequences of the elements in a linear geometry. The design process to fnd the optimal positions of the drones for fight formation and the switch-on interval of each element is carried out by means of the methods of Particle Swarm Optimization and Invasive Weed Optimization. The main contribution to the feld of this paper is a performance evaluation of the design problem for UAVs-based linear antenna arrays considering time modulation in terms of side lobe level (SLL) and sideband levels (SBLs). Simulation results are provided in terms of SLL, SBLs, switching time and positions of the drones. These simulation results illustrate that the time modulation could provide a SLL improvement with respect to previous results in literature. Keywords Linear antenna arrays · Flight formation · Unmanned aerial vehicles (UAVs) · Time modulation · PSO · IWO 1 Introduction Modern unmanned aerial vehicles (UAVs) are of great interest for many military and scientifc applications. Some examples of these applications are remote sensing, transpor- tation of goods, search and rescue, emerging and future com- munication systems, radars, among others. UAVs require a high number of antennas for data and communication links, i.e., UAVs carry a large number of surveillance and communication equipment. In this case, UAVs technology imposes constraints on the platform size (and weight) that limits bandwidth and gain of an antenna element [1]. A real challenge in UAVs is the coverage range. The coverage range is very limited because of the low gain antennas mounted on the aircrafts. Therefore, a concept of intelligent antenna sys- tem needs to be found to guarantee good radiation character- istics and coverage in scenarios limited by interference [2]. Traditionally, each antenna requires its own volume, there- fore limiting the number of antenna elements on a UAV [3]. One possible solution for this limitation is to use an antenna array to increase the gain of the wireless links. Nonethe- less, an antenna array mounted on a single UAV adds more weight, size and power consumptions to the aircraft. A feasible solution to this problem is modelling an antenna array from the operation of UAVs fight forma- tion maintaining an adequate distance to avoid possible collisions [4]. This type of array uses each antenna ele- ment mounted in a single aircraft. This avoids adding more weight, size and power consumptions. The idea of modelling an antenna array from several vehicles has been studied in [4–6]. It was illustrated in the study of these previous works that UAVs technology could take advan- tage from this concept considering optimal positions for UAVs formation fight to have a maximum per formance in terms of directivity and enlarging the range of opera- tion. The previous work illustrated in [7] investigated the use of formations of UAVs as phased antenna arrays. A simple linear control law was proposed in [7] to maintain the objective value close to the optimal when the vehicles * Marco A. Panduro mpanduro@cicese.mx 1 Universidad Autónoma de Tamaulipas, UAMRR-R, Reynosa, Tamaulipas, Mexico 2 Radanter S.A. DE C.V, Reynosa, Tamaulipas, Mexico 3 CICESE Research Center, Ensenada, Mexico 4 Universidad Pública de Navarra, Campus Arrosadia, Pamplona, Spain 5 Department of Electronics and Communication Engineering, NIT Warangal, Warangal 506004, India