Stable Radio Frequency Transfer Over Free Space by Passive Phase Correction

The frequency transmission over free-space link can effectively overcome the dependence of existing optical fiber time-frequency transmission technology on optical fiber network. In this paper, we demonstrate a passive phase correction technique over a 124 m long indoor atmospheric radio frequency (RF) dissemination. This scheme simplifies the system, and suppresses the effects of Rayleigh backscattering. We verify the feasibility of the scheme by transmitting 1 GHz RF signals over the atmospheric link. After timing fluctuation compensation, the relative frequency stability can reach 6.8 × 10
^-15
for 1 s and 3.2 × 10
^-17
for 10
³
s, the RMS timing fluctuation is 186 fs in 5000 s. It can be proved that the scheme is very effective in eliminating phase noise caused by atmospheric link.