Both rain and oxygen can heavily impact signal levels in the 60GHz band.  


Oxygen absorbs the signal in the lower half of the unlicensed 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:





Channel planning


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.


i  Summary: the 60 GHz upper band channels are less affected by oxygen absorption than the lower channels.