MOLECULAR ATTENUATION AND PHASE DISPERSION BETWEEN BETWEEN 40- AND 140-GHz FOR PATH MODELS FROM DIFFERENT ALTITUDES

摘要

Radio wave propagation in the 40 to 140 GHz band through the first hundred kilometers of the atmosphere is strongly influenced by the microwave spectrum of oxygen (O2-WS). A unified treatment of molecular attenuation and phase .dispersion is formulated. Results of molecular physics are translated into frequency, temperature, pressure, and magnetic field dependencies of a complex refractive index. The intensity distribution of the O2-MS undergoes several changes with increasing altitude: when h < 10 km, all lines, but one at 119 GHz, are merged to a continuum spectrum under the influence of pressure-broadening;when h > 30 km, a line spectrum with isolated Lorentzians is displayed;when h > 40 km, Zeeman-splitting of each line occurs due to the influence of the earth' s magnetic field;for h > 60 km, a Voigt pro-the governs the transition to a Gaussian line shape and eventually the Doppler-broadened line spectrum vanishes. The influence 0' water vapor is discussed separately.