GNSS constellations monitoring using a phased array antenna system

Global Navigation Satellite Systems (GNSS) have become indispensable for numerous applications, ranging from the synchronization of critical infrastructure to precise navigation applications. It is imperative to establish reliable monitoring systems that ensure the dependability and security of satellite constellations, given society's increasing reliance on GNSS for accurate positioning, timing, and navigation. This study introduces a cutting-edge GNSS monitoring antenna system which deliver high-performance results.

The antenna system is composed of multiple blocks: a reconfigurable 64 elements dual-frequency (L1/L5) array antenna, filtering stage, amplification and phase shifting stages, signal combiners and a GNSS receiver stage. The proposed antenna is modular, i.e., each component can be controlled independently from the others, allowing easy maintenance and more interestingly, re-configurable antenna specifications. To receive multiple GNSS signals at the same time a custom receiver block has been designed to have 8 RF signal input with each beam created by the antenna connected to a GNSS receiver which is multi-constellations and dual frequency. All the signals are then logged or observed live.

A Raspberry Pi is connected to the receivers to actively control the beams using the publicly available satellites ephemerides (using two-line element files) and changing the phase on each antenna element.

The antenna array is built with 8 panels of 8 elements (2x4 distributions) which can be arranged in multiple shapes. Accordingly, the operator can assemble the panels to have a unique and a very high gain beam or he can choose to create up to 8 sub-arrays, i.e. 8 different beams. These sub-arrays can then be oriented toward different directions to have a full-sky coverage. The shape can also be optimized to achieve a high level of interference and multipath mitigation for GNSS applications. By exploiting the analogue beamforming technique, the beams are steerable which enable the tracking of GNSS satellites.