Table 4. Link power budget of the 20 km experiment [16]

Parameter Equivalent value [dB or dBm]
Tx laser power (200 mW) +23.0 dBm
Tx antenna gain (185 μrad) +86.7 dB
Tx optics loss (beam splitter) –1.0 dB
Free space loss (20 km) –224.2 dB
Atmospheric loss (0.1 dB/km × 20 km) - Clear weather condition @ 1,550 nm –2.0 dB
Rx antenna gain (250 mm) +114.1 dB
Rx loss (beam splitter, secondary mirror, coupling) –7.5 dB
Rx power in fiber –10.9 dBm