Multipath Rejection Capability Analysis of GNSS Antennas

Abstract

Multipath is recognized as a limiting factor for precise GNSS positioning. Therefore, a strong interest in identifying and mitigating it both at antenna and receiver side has led to much research in this topic and solutions being developed and commercialized. However, from the antenna point of view, a clear analysis of the actual antenna multipath susceptibility (or in an opposite way, its rejection capability) for multiple and more complicated cases than single bounce from ground has, to the best knowledge of the authors, not been extensively performed. Scope of this work is therefore to analyze the multipath rejection capability of different antennas (both at L1/E1 and L5/E5a band) in different situations, such as in tripod-like scenarios (hence suffering from multipath from horizontal surfaces) or in scenarios with multipath coming from slanted obstacles or in the vicinity of buildings (hence in cases with multipath coming from vertical surfaces). Such results will then be correlated with the antenna characteristics, in terms for instance of cross polarization discrimination and down-to-up ratio (DUR) and an optimal performance indicator for the different cases will be sought for. It will be shown that the antenna electromagnetic characteristics deterministically determine the rejection capabilities, but also that different parameters shall be taken into account for each category of multipath.