Jerry D. Hopponen; Hans J. Liebe

Abstract: Prediction of propagation effects (i.e., path attenuation, phase delay, ray bending and medium noise) over the 1 to 300 GHz frequency range through the clear, nonturbulent atmosphere is accomplished by combining a spectroscopic data base with a computer program for two dimensional ray tracing. Interactions between the physical environment and electromagnetic radiation are expressed by a complex refractivity N. The quantity N is a function of frequency, pressure, humidity, and temperature. Spectroscopic data supporting N consist of more than 450 coefficients describing local O2 and H20 absorption 1ines complemented by continuum spectra for dry air and water vapor. Height profi1es (up to 80 km) of N–spectra are the basis for calculating propagation effects along a radio path (ground–to–ground, ground–to–aircraft, and ground-to–satellite. The computer model assumes a symmetric, spherically stratified atmosphere without horizontal N gradients. Evaluation of path integrals for radio range, cumulative attenuation, and noise temperature is accomplished in a rapid manner. Various simulated propagation aspects and details of the treatment of the noise integrals are given.

Keywords: millimeter-wave propagation; clear atmosphere; path attenuation and delay; radiances; radio path modeling; ray bending

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