Beamforming performance of satellite swarm-based antenna arrays for 6G direct-to-cell connectivity

Direct connectivity in L/S frequency bands between satellites and common mobile terrestrial user equipment (UE), e.g., smartphones, is an essential feature for future 6G nonterrestrial networks. The use of swarms of satellites in low Earth orbit represents in this context an innovative and promising approach. Swarms are composed of several small and light-weight satellites, e.g., CubeSats with patch antennas, organized in a formation flying to create a distributed phased antenna array. It has the potential to provide an enhanced gain, narrower beamwidth and lower launch/build costs compared to conventional single satellite systems with large reflector antennas. In this work, the impact of key parameters such as the number of satellites in the swarm, their reciprocal distance and the array shape is thoroughly analyzed. It is shown that the undesired phenomenon of grating lobes can be mitigated via optimized array geometries. Furthermore, this work presents a new geometry named enhanced logarithmic spiral array (ELSA).