Arctic SATCOM Coverage : Coverage and Link Budget Analysis of LEO and MEO Constellations for Portable Ground Terminals

Sammanfattning

This study investigates the challenges and design considerations involved in providing stable and portable satellite communication (SATCOM) within the Arctic Circle using Low Earth Orbit (LEO) and Medium Earth Orbit (MEO) constellations. Traditional geostationary (GEO) satellites are hindered at high latitudes by the Earth's curvature, creating a significant connectivity gap in a region with growing strategic and economic importance. The research methodology involved developing simulation models in Python to calculate coverage and performance, which were then validated by a simple convergence test and visually, using MATLAB’s Satellite Communications Toolbox. A core component of the analysis was the definition of a "Threshold Nadir Angle" based on link budget calculations to determine the limits of stable communication for portable terminals. The study primarily focused on a MEO constellation at an altitude of 8,000 km, identified as an effective compromise between latency, satellite lifespan, and constellation size. Key results indicate a significant "uplink bottleneck," in which the limited EIRP (Equivalent Isotropically Radiated Power) of small portable terminals constrains the overall system more than the satellite’s downlink capabilities. Analysis of antenna apertures revealed that while very small antennas (0.05m) provide wide coverage, they are highly susceptible to interference and noise. Conversely, larger antennas (0.45m) offer robust links but prohibitively small footprints. An optimal "middle ground" antenna diameter was identified between 0.20m and 0.25m for a satellite constellation at an altitude of 8000km. The study concludes that achieving reliable Arctic coverage for portable terminals using a simple, fixed-antenna constellation is technically unfeasible. Instead, the results suggest that strategically viable solutions must utilise multi-beam configurations or active beam-steering antennas to dynamically direct bandwidth toward areas of interest.