Calculation of clear air EHF refractivity

A practical calculation procedure is presented for the complex refractivity N of air in the EHF (30 to 300 GHz) region. The absorption line spectra of the major constituents O 2 and H 2 O and of the trace gases O 3 and CO are expressed in a coefficient scheme relating N directly to frequency, dry air and water vapor pressure, temperature, and trace gas number density. The spectroscopic parameters for the O 2 lines incorporate new experimental results obtained from our laboratory studies. The formulation allows radio engineers to make straightforward computations of transfer, shielding, and emission properties for modeled radio paths based upon the physical parameters of the atmosphere.