DESIGN AND IMPLEMENTATION OF A MICROWAVE TRANSMITTER FOR DRONE AIRBORNE CHARGING

• Main Author: Alifa, Lisdatul
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/82321
• Institution: Institut Teknologi Bandung

Unmanned Aerial Vehicles (UAVs), commonly known as drones, are a trending technology with significant potential across various aspects of human life Drones open new opportunities in monitoring, mapping, delivery, and applications in pre- cision agriculture and infrastructure inspection. With advanced navigation and sensors, drones can provide effective solutions in emergency situations such as search and rescue, as well as delivering medical aid to remote areas. However, drones still face several technical challenges that need to be addressed, such as limited flight duration and battery capacity. These limitations can affect opera- tional effectiveness in emergency situations that require continuous monitoring or long-term support. Therefore, a microwave transmitter system has been designed to charge drones as a solution to these technical challenges. This system is called the wireless power transmission (WPT) system. The WPT system enables direct power charging from ground stations to drones operating in the air without needing to land. With this WPT technology, it is expected to improve the reliability and responsiveness of drones in emergency situations, thus providing greater benefits in supporting the safety and well-being of the community overall. Various WPT methods have been researched, such as induction-based, laser-based, and microwave-based WPT. Among these three methods, the microwave method is chosen as the most suitable for use in drones because it can manage the transmis- sion area and has a longer transmission range compared to other methods. To sup- port the microwave-based WPT system, Radio Frequency (RF) power generator components are needed to generate RF power and antenna components to manage the direction and area of power transmission. By integrating these two components, the microwave-based WPT system can be implemented effectively and efficiently. The first step in designing a microwave-based system is selecting the operating fre- quency of the system. To avoid regulations on frequency use, this system will use the Industrial, Scientific, and Medical (ISM) frequency, which is specifically used for research, at 2.45 GHz. Next, for the RF power generator, components capable iv of generating large and stable RF power are required. Magnetrons and transform- ers meet this need. With the input voltage from the transformer, the output voltage from the magnetron reaches up to 900W. Based on these specifications, the antenna specifications, particularly the gain of 17dB, are determined. To achieve high gain, two antenna alternatives can be considered: the Radial Line Slot Array (RLSA) antenna and the horn antenna. The RLSA antenna is known for its high gain, while the horn antenna has a funnel structure that can enhance safety with high directiv- ity. Considering the advantages of each, the decision was made to integrate the RLSA antenna with the horn antenna. The antenna was designed in two stages: the RLSA antenna without horn integra- tion and the RLSA antenna with horn integration. Optimization analysis using CST Studio Suite showed that the horn-integrated antenna performed better than the non-integrated horn antenna at the operating frequency of 2.45 GHz. Therefore, production was carried out on the RLSA antenna integrated with the horn. Meas- urement results showed a reflection coefficient (S11) value of -32.67 dB with a bandwidth of 900 MHz. The VSWR parameter showed a value of 1.039, while the radiation pattern parameter showed an HPBW value of 20° with an antenna gain of 17.32 dBi. Comparison between simulation and measurement results showed dif- ferences due to fabrication imperfections, material variations, and environmental influences. The RF power generator output power measurement was 58.17 dBm, and the trans- mitter system output power measurement showed an output power of 66.23 dBm, resulting in a transmitter antenna gain with the magnetron as the power source of 8.06 dBi. Signal reception measurements at varying distances showed the strongest signal reception at a distance of 2 meters at 13 dBm, although this measurement was in the near field area. Meanwhile, angle variation measurements at a distance of 5 meters showed radiated power at 90° from the radiation axis below 0.1 mW/cm2.