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Antenna Arrays, Smart Antennas, Satellite Constellations, Low-Earth Orbit, mmWaves. abstract Half of the world’s population is not yet online, essentially due to the lack of infrastructures. Supported by many great investors in the space industry, Low-Earth Orbit (LEO) satellites are being distributed by the thousands and the networks established between them will allow to broadcast internet throughout the globe. A key aspect for the success of such technology is the capacity of each ground terminal to properly track and follow a moving satellite, forcing their antennas to redirect their beam direction until a better satellite option arises. In LEO satellite constellations, the time that the satellite is in line of sight with a ground station is a few minutes, making the mechanical orientation of the radiation beam more prone to greater wear, while the electronic alternative represents greater flexibility and faster adjustment. As such, phased-array antennas become a much more attractive solution to obtain an antenna terminal that meets the technical requirements of LEO satellite constellation communication systems, particularly, the electronic beam steering requirements. As such, this thesis’ main goal is to obtain two 16-element phased-arrays, one transmitter (Ka-band) and one receiver (K-band). These phased-array antennas were developed having in mind the constraints of their integration in a base station transceiver. Therefore, the main contributions of this work are focused on the radiating component of both phased-arrays and how it is affected by the overall system. Suitable solutions are herein proposed regarding the radiating elements, the arrays’ structure, the circular polarization strategy and the feeding techniques used. A multilayer dielectric stack implementation was suggested, considering the antenna integration and the overall radiofrequency (RF) structure optimization, to further enable a modular implementation. Additionally, topics such as the mutual coupling impact and its mitigation, along with a new concept to obtain multi-band antennas were also addressed as strategies to further maximize the phased-arrays prototypes performance. |
