Both rain and oxygen can heavily impact signal levels in the 60GHz band.
Oxygen absorbs the signal in the lower half of the light licensed 60GHz band with a peak at channels 2 and 3 of around 15dB/km at sea level.
This amount varies based on altitude since altitude also has an impact on the amount of oxygen in the path.
Channel 1 is less impacted by oxygen absorption at around 12dB/km and channels 5 and 6 are minimally impacted by oxygen absorption as shown in the graph below:
These physical characteristics can be very useful when planning deployments:
- For high densities of shorter links using the channels with high oxygen absorption results in less self-interference and a higher amount of channel reuse since the oxygen is eliminating the signal quickly past the usable range.
- For longer links, the upper channels enable longer connections.
Summary: the 60 GHz upper band channels are less affected by oxygen absorption than the lower channels.