SNR Optimization for LEO Satellite at Sub-THz Frequencies

The next generation of satellite constellations would include low Earth orbit (LEO) satellites with communication link above 100 GHz in order to achieve higher efficiency and capacity of the satellite networks due to large available bandwidth. The LEO satellites require tracking by the ground station receiver; however, due to the complexity, inefficiency, and nonlinearity of the phase shifters at terahertz (THz) frequencies, the conventional concept of scanning phased array antenna is less recommended. In this work, we derive an optimization algorithm for an electronically switchable subarray of phased array at the ground station that maximizes the signal-to-noise ratio (SNR) depending on the range of elevation angles of satellite. The algorithm optimizes the SNR by adapting the interelement spacing between array elements considering the impact of molecular absorption loss and noise, thermal noise from the sky and the ground. In comparison to uniform phased array design with equal spacing, the SNR can be improved for a typical scenario by about 3 dB and thus improving the link performance. To the best of our knowledge, this LEO satellite communication algorithm at the sub-THz frequencies is for the first time to be published.