A study of antenna multipath instabilities in two-way satellite time and frequency transfer

The two-way satellite time and frequency transfer (TWSTFT) has been one of the major tools for atomic clock comparison in the international time community. The performance of TWSTFT nowadays has reached the level of nanosecond. For the further better performance achievement, it is worth studying the instability sources which may contribute to diurnal time residual of TWSTFT. This study conducts an analysis about time errors caused from three antenna multipath cases including reflection, diffraction, and ordinary-extraordinary waves. The results show that the antenna multipath error should not be the essential instability source of diurnal time residual. Since the antenna multi-path error is just a minor instability source, other sources should be considered in future study. We make a recommendation to study temperature dependence, such as that of the multipath interference through cables and that of the transponder of geostationary satellite.