On site validation in GNSS stations for multipath and interference mitigation structure (IMLP)

The mitigation of Interference and Multipath is of paramount importance for the GNSS reference stations since they potentially introduce significant errors on the measurements provided by these stations. The solution that has been used up to now in order to reduce the effect of multipath consists of using a small choke-ring ground plane, but unfortunately this solution results to be effective only to a very limited extent. The solution proposed in this paper, named "Interference and Multipath Protector" (IMLP), consists instead of adding an external structure able to deterministically change the antenna coverage. The general - effect of the IMLP structure is: - to reduce the unwanted gain at low elevation angles; - to leave the original pattern as much as possible unchanged for the high elevation angles. The paper summarizes recent simulation analyses and measurements results deriving from the study (design and development) of the IMLP structure solution.