New space satellite communications

• Autor(a) principal: Gomes, Rodrigo Branco
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/38987
• topic: Butler matrix; Beamforming; Multibeam antenna; Satellite

In recent years, Low Earth Orbit satellites, also known as satellite constellations and Internet from space have become hot topics. For that, many established satellite operators such as SpaceX and Amazon have recently filed applications for these types of constellations with novel architectures that rely on thousands of high-throughput satellites, combined with an even-larger ground segment, which will compete with and complement the terrestrial Internet infrastructure where it is inefficient or non-existent. For that, multiple beam antennas are identified as a critical technology for the 5G, the 6G and more generally beyond 5G wireless communications links in both terrestrial networks and non-terrestrial networks. Multibeam antenna systems operating in the millimeter-wave frequency bands have attracted a lot of interest and have been actively investigated. They represent the key technology for supporting high data transmission rates, an improved signalto- interference-plus-noise ratio, an increased energy and spectral efficiency, and versatile beam shaping, enabling beamforming and massive MIMO. To reduce the cost and power consumption, there is a special industrial interest in adopting analogue multiple beam antenna array technology. An important sub-system in many of such antenna arrays is the circuit type beamforming network such as Butler matrix, Blass matrix, Nolen matrix, and Rotman lens, mostly at millimeter-wave frequencies. In this work these circuit-type beamforming networks are discussed and compared with higher incidence in the Butler matrix with four input ports and four output ports which is able of steer four independent beams to four different directions depending on which input port is being excited. As proof of concept a 4x4 Butler matrix operating in the 28-GHz band was carefully designed using microstrip technology in which each component was individually optimized and integrated with four patch antennas at the outputs of the network.