ItuRPropagation.P840 (ITU-R Propagation v0.6.1)

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ITU-R P.840: Attenuation due to clouds and fog.

This module implements the method for predicting attenuation due to clouds and fog on Earth-space paths.

The model calculates the specific attenuation coefficient K_l (dB/km per g/m^3) based on the complex permittivity of water, which depends on frequency and temperature.

Reference

ITU-R P.840-7: Attenuation due to clouds and fog. https://www.itu.int/rec/R-REC-P.840/en

Summary

Functions

cloud_attenuation(frequency_ghz, elevation_deg, liquid_water_content_kg_m2, temperature_c \\ 0.0)

Compute cloud attenuation along a slant path.

specific_attenuation_coeff(frequency_ghz, temperature_c \\ 0.0)

Compute the specific attenuation coefficient for clouds and fog.

Functions

cloud_attenuation(frequency_ghz, elevation_deg, liquid_water_content_kg_m2, temperature_c \\ 0.0)

@spec cloud_attenuation(float(), float(), float(), float()) :: float()

Compute cloud attenuation along a slant path.

Parameters

  • frequency_ghz - Frequency in GHz
  • elevation_deg - Elevation angle in degrees (> 0)
  • liquid_water_content_kg_m2 - Integrated liquid water content in kg/m^2 (L)
  • temperature_c - Cloud temperature in degrees Celsius (default: 0.0)

Returns

Cloud attenuation in dB.

specific_attenuation_coeff(frequency_ghz, temperature_c \\ 0.0)

@spec specific_attenuation_coeff(float(), float()) :: float()

Compute the specific attenuation coefficient for clouds and fog.

Calculates K_l (dB/km per g/m^3) as defined in ITU-R P.840-7.

Parameters

  • frequency_ghz - Frequency in GHz (up to 1000 GHz)
  • temperature_c - Temperature in degrees Celsius (default: 0.0)

Returns

Specific attenuation coefficient K_l in (dB/km)/(g/m^3).