The main propagation effect on interference between adjacent Earth‐space paths is differential rain attenuation. In the present paper, a revised method to predict the rain differential attenuation statistics is proposed which is based on a model convective rain cell structure of the rainfall medium and the assumption that the point rainfall statistics follows a lognormal form. Moreover, the revised model analyzes the general problem of differential attenuation taking into account the difference of elevation angles of the slant paths under consideration. The numerical results are referred to the interference problem from an adjacent satellite located in symmetrical geostationary positions in relation to the intended satellite and examine the significance of the difference of elevation angles for various parameters of the problem.

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Abstract. One of the main propagation effects on interference between adjacent Earth-space paths is considered to be the differential rain attenuation. In the present paper a method to predict differential rain attenuation statistics, valid for single-site communication systems, is extended to include double-site interfered systems operating under the dual-polarization mode. The extended procedure is again based on a model of convective rain cells as well on the lognormal model for point rainfall rate statistics. Numerical results are presented referring to realistic diversity systems operating under the hypothesis of using both single and dual polarization and suffering from differential rain attenuation. Some very useful conclusions are deduced on the reliable and economic design of future communication systems where orbital and frequency congestion are quite expectable.

Abstract-The two-dimensional problem of horizontally polarized wave scattering from an air-ground interface is considered. The diffraction problem is formulated by means of the extinction theorem, leading to a system of two simultaneous surface integral equations. The small-slope approximation has been used to solve this system. This solution was used as a fast forward solver in the Monte Carlo simulations of the scattered field near to the rough interface. Properties of the reflected field have been investigated for a single realization of the rough interface as well as for a statistical ensemble of such interfaces. Special attention has been paid to the phase of the reflected field (in the case of a single realization) and to the variance of the reflected field (in the case of a statistical ensemble), which has direct relation with the surface clutter in ground penetrating radars. A principal possibility to retrieve a surface profile from interferometric measurements of the reflected field near the surface is demonstrated.

Scattering of TM waves from a cylindrical scatterer embedded inside a two-layer lossy ground under the assumption of a sinusoidal air-ground interface is investigated. The problem is formulated via an integral equation approach combined with the extended boundary conditions method. The integral equation over the cross section of the scatterer is transformed into an infinite set of linear equations for the expansion coefficients of the unknown magnetic field inside the scatterer. This set is truncated and solved numerically. The numerical results obtained for the far-zone scattered field show that it is is mainly affected by the characteristics and the position of the scatterer with respect to the dips and lifts of the rough surface as well as by the conductivity of the surrounding ground layers. In certain cases the scattering pattern provides useful information about the position and the type of possible buried scatterers.

Abstract. The two-dimensional problem. of horizontally polarized wave scattering from. an airground interface is considered. The diffraction problem is formulated by means of the extinction theorem., leading to a system of two simultaneous surface integral equations. Three perturbation techniques, namely the small-perturbation method, the phase perturbation method, and the smallslope approximation, have been applied to this system.. Iterative relations for the terms of arbitrary order are obtained for each perturbation series. For the sinusoidal surface a benchmark solution, which remains stable near the points of Wood's anomalies, is developed. It is used to establish the area of validity of each perturbation technique by means of numerical comparison.

The problem of scattering from a conducting cylinder above a lossy medium having a sinusoidal profile interface is investigated by combining an integral equation approach with the extended boundary condition method. The incident transverse magnetic electric field and the Green function of the problem are determined by applying the extended boundary condition method. The application of the method of moments to the integral equation over the cross section of the scatterer results in an infinite linear set of equations for the unknown expansion coefficients of the electric field inside the scatterer. This infinite set is truncated and solved numerically. Finally, the far field scattered in free space is evaluated by employing the steepest descent approximation, and several interesting conclusions concerning the influence of the sinusoidal profile on the scattered field are deduced. 883

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