Get REady for NExt Generation of GNSS ANTenna systems (RENEGANT)

• Applicants: Dr. Stefano Caizzone; Professor Dr.-Ing. Steffen Schön
• Subject Area: Geodesy, Photogrammetry, Remote Sensing, Geoinformatics, Cartography ; Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 571471715

The performance of receiving antennas determines not only the sensitivity to the useful information of signals from Global Navigation Satellite Systems (GNSS), but also to the most prominent error sources that prevent safe and accurate positioning, namely multipath and interference. New types of antenna designs have been developed in recent years to cope with these issues: Multi-Antenna Arrays can counteract the effect of interference through beam steering technology, now also available for the civilian market including civil aviation. A second major technology trend goes towards miniaturized, high-performance antennas that can be integrated in mobile and automated platforms (such as drones, cars, cubesats, …) while supporting multiband signals and hence high accuracy applications. Both antenna technologies are gaining momentum in the GNSS research and application, but, the current techniques for characterizing antenna phase center variations and group delays in the geodetic community are focusing on single element (geodetic) antennas and cannot be directly transferred to multi-antenna or small antennas. Reasons are an incomplete understanding of the behavior of antenna characteristics for multi-element arrays as well as the complex interactions between antenna and calibration apparatus: miniaturized antennas often have very limited ground planes; also multi-antenna systems often have antenna elements close to edge of their metallic ground plane. In such conditions, the (near field) multipath and installation susceptibility of such systems can be foreseen to be quite strong. Moreover, their antenna patterns are much less regular and smooth than canonical geodetic antennas, posing a further challenge in the correct estimation and modelling of the antenna patterns. Hence, a new accurate antenna characterization concept is needed to treat non-geodetic antenna types such as multi-antenna arrays as well as miniaturized antennas. The Institut für Erdmessung (IfE-LUH) and the DLR Institute of Communications and Navigation team together to tackle these new challenges. The successfully partnership, already established in the DFG project MAESTRO, will exploit their complementary competences: IfE (antenna calibration in the field and analysis of geodetic infrastructure) and DLR-KN (multi-antenna array design, antenna calibration in anechoic chamber, aviation) to close the knowledge gaps and gain fundamental insights in antenna characterization by 1. Developing a new robot-based calibration strategy to characterize multi-antennas arrays with real GNSS signals, 2. Investigating methods and structures/holders to make the antenna calibration apparatus themselves having a reduced impact on the pattern of the AUT, 3. Exploring how to make best use of the calibration of miniaturized antennas or multi-antenna arrays for final users, i.e. how to guarantee that the antenna calibration can be used reliably once the antenna is installed on its final platform.

• DFG Programme: Research Grants