System latency performance of mechanical and electronic scanned antennas for LEO ground stations for IoT and internet access

There are at least two choices for the gateway ground station antenna scanning function for low earth orbit (LEO) satellite constellations: mechanical or electronic scanning. This article is a comparison of these two options for the system parameter of latency. Since LEO satellites move across the sky from horizon to horizon simple fixed position ground antennas cannot be used for high data channels. Rather, the ground station must scan its antenna from satellite to satellite as they move into and out of the access range of the ground station. Mechanical scanning antennas physically rotate the antenna in two directions. Electronic scanning uses a fixed position antenna and steers the antenna beam electronically to remain pointed at the satellite. This work analyzes the scanning rate of the mechanical and electronic steered antennas. Since latency is a primary concern for real time internet of things (IoT) devices and internet access, it is used as the performance metric. The results show that mechanical scanning antennas increase the overall system latency due to the slew time required to reposition the antenna from one satellite to the other. This work concludes with a summary of the analysis and recommendations for additional analysis.