An exploration of low-cost LNA systems intended for LEO satellites

Abstract

The increasing demand for low-latency, on-demand services has warranted the transformative shift from satellites placed in geostationary orbit (GEO) to low Earth orbit (LEO). To achieve coverage comparable to that of GEO satellites, LEO satellite constellations such as Starlink require thousands of satellites, potentially leading to substantial costs if using traditional space-qualified electronics. However, compared to those in GEO, the less stringent reliability requirements for satellites in LEO have sparked interest in identifying low-cost solutions for various system modules, including low-noise amplifier (LNA) systems. This project seeks to explore low-cost alternatives to the Ka-band LNA hybrid developed at Beyond Gravity in Gothenburg. These alternatives were to be based on commercial off-the-shelf (COTS) components, commercial printed circuit board (PCB) materials, and various design strategies aimed at reducing the overall system cost. The project aimed to compare these cost-effective alternatives with a current high-reliability implementation, to assess the design trade-offs between cost and performance. Also, the project aimed to establish what criteria a design option must fulfil to be deemed suitable for use in LNA systems intended for LEO satellites, as well as highlight the industry-related challenges that hinder the full adoption of the New Space paradigm. The design process consisted of distinct phases, ranging from an initial screening of possible component configurations to the design and optimisation of the final system implementations. The project resulted in two system alternatives: one that incorporates the existing WR28 isolator and has the potential to reduce costs to approximately one-fourth of the original design, and another that explores a system using a quadrature hybrid coupler (QHC) configuration, which offers a tenfold reduction in cost. We believe that the greatest potential to reduce cost lies in replacing the expensive isolators. However, the primary challenge is to maintain sufficient return loss without compromising the system’s noise figure.