INTERGEO Agenda - english

Antennas for receiving signals from Global Navigation Satellite Systems (GNSS) are the first element in the GNSS data processing chain. The antenna performance determines not only the sensitivity to the useful GNSS signal information, but also to the most prominent error sources that prevent safe and ac- curate positioning, namely multipath and interference. The issue of interference is also present at larger distances from conflict regions, affecting civilian geodetic infrastructure and civil aviation. Jamming and spoofing call for more resilient GNSS antenna designs, with multi-antenna systems being among the most effective countermeasures for achieving robust GNSS performance. For highly precise and accurate GNSS-based positioning, Phase Center Corrections (PCC) and Code Phase Corrections (CPC) need to be applied. The determination of these corrections is known as an- tenna calibration and can be done either in the field using a robot and real GNSS signals or in an anechoic chamber using artificially generated signals. In our contribution, we briefly introduce the main objectives of the project RENEGANT (Get REady for NExt Generation of GNSS ANTenna systems). It is a collaborative DFG-funded project between the Institut für Erdmessung (IfE) and the Institute of Communications and Navigation at DLR. The project aims to develop a novel robot-based calibration methodology using real GNSS signals to characterize multi-antenna arrays, while simultaneously investigating the impact of calibration setups, particularly for miniaturized antennas, on CPC and PCC. This contribution presents first comparisons between calibrations of a small u-blox ANN-MB1 an- tenna on a robot at IfE using real GNSS signals and calibrations of the same antenna conducted in a semi-anechoic chamber at DLR. Observed differences are discussed in terms of signal noise, near-field effects induced by the robot platform, and potential impact from the antenna holder used in the chamber environment. Furthermore, first calibration results for individual elements of a Controlled Reception Pattern An- tenna (CRPA) array are presented. The estimated phase center locations of these elements are visualized, highlighting the importance of accounting for active components, such as Low Noise Amplifiers (LNAs), which may significantly influence CPC and PCC due to their electromagnetic interaction with the receiving antenna elements.