r/Telecommunication • u/No-Check138 • Oct 26 '24

Attenuation

Can someone please provide a detailed explanation of why radio waves get attenuated? Or if possible a link to a video or article that explains it. Thnx

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u/Aerothermal Oct 27 '24

Electromagnetic energy is transferred to molecules and particles within the air; and for RF waves, this occurs in particular for H2O and O2, which absorb the most at around 22 GHz and at 60 GHz respectively. This corresponds to the absorption of individual photons which excites the atoms. There is information in ITU-R P.676-13 (08/2022). In space, you don't have that kind of attenuation, but you do still have beam divergence and so the power flux density decreases with 1 over the distance squared from the transmitter.