# Exploring Carbon-Fiber UAV Structures as Communication Antennas for Adaptive Relay Applications
###### Abstract
The authors of the following studies propose various approaches to improve UAV communication and antenna integration: The authors of [9] presented a four-element linear antenna array embedded in a UAV wing structure, operating in the 2.4 GHz ISM band, which enhances link throughput through beam-forming techniques that reduce signal loss and minimize errors sent over long distances, but in an open field [10]. Additional measurements from this study demonstrated that integrated antenna arrays can significantly improve spectral efficiency under controlled conditions. The authors of [11] provided a comprehensive survey on quadcopter frame-based antennas and electromagnetic field measurements, highlighting the advantages of UAVs in evaluating large-scale antenna arrays and 5G/6G channel models while addressing challenges such as UAV vibrations and positioning accuracy due to errors in the GPS system [12]. Their analysis further reveals that UAV-based measurements offer a cost-effective alternative to conventional fixed antenna testing setups. The authors of [13] investigated UAV-based antenna calibration for polarimetric weather radars, identifying the impact of scattering effects from the UAV frame and proposing the use of more directive probe antennas for increased measurement accuracy [7]. This work underlines the necessity for precise calibration techniques to minimize measurement errors, especially in harsh weather conditions. Building on these findings, this paper explores the feasibility of using a UAV's carbon chassis as an antenna, enhancing communication efficiency in UAV applications. Building upon this existing body of work, the present paper investigates a novel and cost-effective approach for enhancing UAV communication systems: the use of the UAV's carbon-fiber chassis as an integrated antenna [14]. Preliminary simulation results reveal that the carbon-based structure enables broad operational bandwidth and produces a stable radiation pattern, positioning it as a strong candidate for embedded antenna design in UAV systems. To experimentally validate this concept, two cylindrical monopole antennas were fabricated and evaluated in terms of bandwidth, impedance matching, radiation pattern, and gain. All testing followed industry-standard protocols to ensure the accuracy and reliability of the measured data. For ease of testing and reproducibility, the experimental setup focused on a single UAV arm composed of a cylindrical carbon tube mounted on a metallic support [15]. The active antenna structure included the full length of the black carbon-fiber tube and a small metallic rod terminating at the metallic ground plane. The tube measured 16.9 cm in length and 1.5 cm in diameter. Its support assembly consisted of four metallic legs, each 4.5 cm long, forming a circular base with a diameter of 35 cm. Beyond characterizing the antenna's electromagnetic performance, this work also proposes the integration of a UAV-based relay station capable of dynamically adjusting its altitude to improve communication with delivery drones. Such a relay system would autonomously adapt to environmental conditions and line-of-sight constraints, enhancing signal propagation and overall network robustness. By reducing the need for fixed-ground infrastructure and human intervention, this solution would significantly increase the efficiency and scalability of drone-based delivery networks. The combined results from simulations and measurements strongly support the feasibility of this approach, offering a promising direction for the development of integrated UAV antenna systems that optimize size, weight, power, and operational capability [16, 17].