Hans J. Liebe, George A. Hufford, and Michael G. Cotton

Abstract:

Millimeter-wave propagation through the nonprecipitating atmosphere is modeled for frequencies below 1000 GHz. Complex refractivities represent the spectral properties of four natural absorbers; that is, oxygen, water-vapor, suspended droplets and ice particles. The dry-air model is supported by new, extensive 60-GHz laboratory absorption measure­ments of the pressure-broadened O₂ spectrum. The water-vapor model considers contributions of 30 local H₂O lines, which are supplemented by an empirical continuum term based on laboratory measurements in the 138- to 213-GHz range. Revised formulations for the complex permittivities of water and ice are employed in the suspended-particle model which, due to the Rayleigh approximation, provides only minimum estimates above 300 GHz.

Keywords: millimeter-wave propagation; propagation modeling

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