A modified simplified model for atmospheric gaseous attenuation

摘要

The simplified model in versions 1 and 2 of Recommendation ITU-R PN. 676 for specific attenuation due to atmospheric gases for sea level does not apply ot higher altitudes. A possible model for specific attenuation derived from the zenith attenuation equation in the Recommendation does not too. A modified model is therefore presented, which is based on both simplification of and curve-fitting to the MPM model, A comparison is made among the three simplified models against the MPM model, and the modified model is found in excellent agreement with the MPM model for altitudes up to 5 km at least.