Adaptive digital-beamforming antennas with navigation receiver for Galileo applications

Kurzfassung

The request for future Galileo-Applications with high level navigation accuracy and system integrity leads to a demand of new system and hardware developments. Current GPS-systems in the upper and lower L-band with omni-directional antennas show performance limits. Multiple reflections in the users environment are known as the dominant contribution of signal and accuracy degradation. For some security applications also jammer signals have to be considered. Improvements in the domain of signal processing are one method to detect and suppress these effects to a decent level. Future navigation systems with active high gain steerable antenna arrays can increase the initial navigation accuracy by tracking the visible satellites with multiple beams. Adaptive Antenna Arrays with digital beamforming (DBF) are offering a very flexible approach to build up such smart stand-alone systems for Galileo The beamforming and -steering capabilities can provide the required sidelobe control and nulling of jammers. A multi-channel navigation receiver can be implemented together with the beamformer hardware as feedback-loop, controlled by smart algorithms in the digital domain. A proposal for the development of DBF antenna demonstrators in L- and C-band, including antenna and RF-receiver electronics, signal processing hardware and beamforming algorithms will be presented. The antenna elements in L-band have to provide a very large bandwidth in connection with reasonable polarization purity over the band. Satellites close to the horizon have to be covered without too large losses in the performance. Calibration capabilities inside the DFB-hardware is important to control the overall system integrity. Main focus of the presentation will be the development of broadband Antenna-Arrays in the upper and lower Galileo and GPS L-band, as well as the suggested but not yet implemented narrowband Galileo-service in C-band. First concepts of the RF- and signal processing architecture will also be shown.