Sky Radio Quiet Zones for Mitigating RFI From Large-Scale NGSO Satellites to Ground Radio Astronomy System

Emerging large-scale non-geostationary orbit (NGSO) satellite communication (SatCom) systems with more than thousands of satellites raise a serious concern of radio frequency interference (RFI) to the ground-based radio astronomy system (RAS). This situation becomes more serious as the SatCom industry is rapidly expanding the number of communication satellites which increases RFI, while the RAS is also advancing with enhanced radio astronomical observation (RAO) capability requiring better protection against RFI. To address this impending RFI issue, we analyze the corresponding RFI to identify dominant RFI contributors and then propose two types of sky radio quiet zone (SRQZ), namely, telescope-centered (TC)-SRQZ and RAO direction-centered (DC)-SRQZ. We investigate peak RFI and average RFI suppression characteristics of the two SRQZ types when applied individually alone and jointly. We evaluate the RFI characteristics with/without SRQZs for a few representative ground RAS receiver locations under a low earth orbit SatCom system as well as a medium earth orbit SatCom system. We present and discuss extensive RFI performance results and their dependency on the specifics of the RFI scenarios. These results show that appropriately designed SRQZs provide significant RFI suppression. We also offer guidance on the choice of SRQZ type/deployment, related parameter settings, and practical implementation aspects.