Spatial Filtering of Multipath at GNSS Reference Stations Through Metamaterial-Based Absorbers

Reference stations for (satellite or terrestrial) navigation are often showing performance reduction due to multipath effects, caused by reflecting objects in their vicinity (buildings, vegetation, big antennas at spaceports, etc.). A possible solution to this problem is to use absorbers in the vicinity of the reference station antenna, to selectively suppress signal reception (and reflections) from nearby objects. This article describes the design, measurement, and preliminary test of a metamaterial-based absorber for this purpose, based on the combination of split cross ring resonator and cave cross resonator: the absorber has been characterized both electromagnetically as well as through field tests in the vicinity of a global navigation satellite systems reference antenna, showing a suppression of more than 50% of the strong multipath-due pseudorange errors.