Radio Regulations

Source: the Radio Regulations published by the International Telecommunication Union (ITU).

All IBR Recommendations
P

Recommendation ITU-R P.838-3

Mandatory (1992-1999-2003-2005)

Specific attenuation model for rain for use in prediction methods

View official text at ITU

Version history

Version evolution

The number in each cell (e.g. −9) is the Recommendation's revision number — the “-9” in ITU-R M.585-9, not a negative value. So −8 → −9 means the binding reference moved from the 8th to the 9th revision.

RR-2008 -3
RR-2012 -3
RR-2016 -3
RR-2020 -3
RR-2024 -3

Incorporated into the RR by

RR provisions, footnotes and Resolutions that incorporate this Recommendation

Appendix

Appendix 30A

Provision

2.2

Scope

there is a need to calculate the attenuation due to rain from a knowledge of rain rates,

Recommends

  1. that the following procedure be used.
  2. The specific attenuation γR (dB/km) is obtained from the rain rate R (mm/h) using the power-law relationship:
  3. γR=kRα (1)
  4. Values for the coefficients k and α are determined as functions of frequency, f (GHz), in the range from 1 to 1 000 GHz, from the following equations, which have been developed from curve-fitting to power-law coefficients derived from scattering calculations:
  5. log10k=j=14ajexp−log10f−bjcj2+mklog10f+ck (2)
  6. α=j=15ajexp−log10f−bjcj2+mαlog10f+cα (3)

+23 more in the full text

Source: ITU Radio Regulations, editions of 2008, 2012, 2016, 2020 and 2024. The English, French and Spanish texts are each taken from the official edition in that language, not translated from one another. Sources and citation.