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An empirical model has been generated to estimate diversity gain on earth‐space propagation paths as a function of earth terminal separation distance, link frequency, elevation angle, and angle between the baseline and the path azimuth. This analysis utilized 34 diversity experiments which have been conducted in Canada, England, Japan, and the United States during the past decade. The resulting model reproduces the entire experimental data set with an rms error of 0.73 dB. The separation distance dominates the dependence of the diversity gain. The dependence on link frequency is small but significant. No identifiable dependence on baseline orientation was found.

A technique is presented for the calculation of the oblate and prolate spheroidal wave equation eigenvalues and eigenfunctions. The eigenvalue problem is cast in matrix form and a tridiagonal, symmetric matrix is obtained. This formulation permits the immediate calculation of the eigenvalues to the desired accuracy by means of the bisection method. The eigenfunction expansion coefficients are then obtained by a recursion method. This technique is quite simple to program, and the computation speed is rapid enough to allow its use as a function subroutine where values not previously tabulated or large numbers of values are required.

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This paper contains the results of a radar study of path diversity performance on simulated earth‐space communication links in the presence of rainfall. The McGiIl University 3 GHz radar was used to obtain three‐dimensional fields of radar reflectivity. The radar reflectivities measured at resolution cells along the propagation paths of interest were converted to specific attenuation and these values of specific attenuation were then summed to yield the total path attenuation. This procedure was repeated along parallel earth‐space paths to yield the path diversity performance. The results for the Montreal area indicate that path diversity performance is mildly dependent upon the orientation of the propagation path and weakly dependent upon the baseline orientation of the ground diversity terminals.