GNSS antenna multipath effects

This paper is presenting results from experiments aiming at quantifying the multipath effects on GNSS antennas in some moderate and extreme implementation cases. In Observatoire de Paris (OP), the multipath due to a metallic plate nearby the GNSS antenna might generate a relative calibration offset reaching about 3 ns on P-code delays. But proper Common-View (CV) software is able to get rid of such offsets, reaching P3 CV deviation mean values below 100 ps. At the Royal Observatory of Belgium (ORB), with three different receiver types, different antenna positions are showing that P-code offsets might reach about 350 ps in P1 and 750 ps in P2, hence a significant bias in relative calibration results. The results are showing that a more extensive work is required before trying to fix an upper limit for the multipath uncertainties in the guidelines uncertainty budget for GNSS relative calibration.