Abstract
A numerical solution of the radiative transport equation is given for a plane-parallel rain medium in connection with the estimation of the incoherent effect on attenuation and cross-polarization of a millimeter wave due to rain. The method of solution consists of an extension of the spherical harmonics method. An assembly of spherical raindrops is considered. From the analysis, it is found that the exact expression of Mie scattering can be incorporated into the integral term of the transport equation, thus allowing the integral to be evaluated without approximation. Preliminary calculations are performed at 34.8 and 82 GHz. Circular polarizations are considered. The results include the directional patterns of reflected and transmitted incoherent intensity, both for left-hand and right-hand circular polarizations, the effect of drop size on the directional patterns, the incoherent signal intensities within the rain medium, and so on.
Analyse
Une solution numérique de l’équation de transfert radiatif est donnée pour un rideau de pluie en vue d’estimer la contribution de la diffusion incohérente à l’atténuation et la transpolarisation d’une onde millimétrique causées par la pluie. La méthode de résolution est une extension de la méthode des harmoniques sphériques. Pour un ensemble de gouttes sphériques, l’analyse montre que l’expression exacte de la diffusion de Mie peut être introduite dans l’intégrante de l’équation de transfert. Donc, l’intégrale peut être évaluée sans approximation. Les calculs préliminaires sont effectués à 34,8 et 82 GHz avec des polarisations circulaires. Les résultats contiennent les diagrammes de directivité de l’intensité incohérente réfléchie et transmise pour les polarisations circulaires droite et gauche, l’influence de la dimension des gouttes sur ces diagrammes, les valeurs des intensités incohérentes du signal dans le milieu pluvieux, etc.
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Oguchi, T. Effect of incoherent scattering on attenuation and cross-polarization of millimeter waves due to rain: preliminary calculations at 34.8 and 82 GHz for spherical raindrops. Ann. Télécommunic. 35, 380–389 (1980). https://doi.org/10.1007/BF03003516
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DOI: https://doi.org/10.1007/BF03003516