The depolarization effects of Earth-Space link at MMW Bands
The depolarization effects of Earth-Space link at MMW Bands and their mechanisms are analysed. The models to evaluate XPD induced by clear atmosphere, rain, ice crystals, snow, sand-dust storm and ionized layer are summarized and analysed. The methods to calculate total XPD including the influence of transmitting antenna are discussed. The results given in this paper are important for frequency resue and depolarization MIMO techniques.
Disponibilité des liaisons hertziennes numériques utilisant des polarisations croisées a la même fréquence
AnalyseUne étude est faite sur la disponibilité des liaisons utilisant les mêmes fréquences sur des polarisations croisées. Elle présente une méthode simple de calcul de la réduction de la disponibilité due à l’existence des trajets multiples dans le cas de la réutilisation de fréquence. Après avoir souligné l’influence des caractéristiques de l’antenne en polarisation croisée, la réduction de la disponibilité est calculée à partir de résultats de mesures de découplages de polarisations effectuées sur différentes liaisons expérimentales.AbstractA study is made of the availability of links operating at the same frequencies with cross polarization. A simple method of computation is presented showing how the availability is reduced due to multipath propagation in the case of frequency reutilization. After having pointed out the effect of the characteristics of the antenna with crosspolarization, the reduction is availability of calculated from results of polarization decoupling measurements carried out on various test links.
The Probability Distribution of the Amplitude of a Constant Vector Plus a Rayleigh-Distributed Vector
Formulas, tables, and graphs are given for the probability distribution of the instantaneous resultant amplitude of the sum of a constant vector and a Rayleigh-distributed vector. It is emphasized that two distributions are required to describe a Rayleigh-distributed vector: the distribution of its amplitude and the distribution of its phase. A summary is presented of physical conditions which must be satisfied for a given phenomenon to exhibit statistical properties of a Rayleigh-distributed vector. References are made to ways in which these distributions may be used to describe random variables occurring in ionospheric, tropospheric, and irregular terrain propagation problems. Finally, a discussion is given of amplitude and phase distributions of two other random vectors encountered in tropospheric propagation studies.