On the problem of high-accuracy modeling of the dry air absorption spectrum in the millimeter wavelength range

A detailed analysis of the dry air spectrum in the frequency range 180-260 GHz is given. The contributions of monomolecular and bimolecular absorption are discussed. It is shown that the effect of collisional coupling of zero-frequency transitions has a significant impact (up to 60%) on the value of nonresonance absorption. The coefficients of the empirical approximation of the "dry" continuum are redefined. A comparison with the continuum approximation from the Millimeter-wave Propagation Model is given.