Spatial correlation function of the sky wave for use in space diversity reception

Abstract

Fading is a serious problem in HF communication. It is caused primarily by the random irregularities in the refractive index of the ionosphere. One of the successful solutions to this problem is the space diversity reception. In this work the spatial correlation function of the received signal fluctuations is derived using geometric optics and single scattering approximations. Then the correlation function is used to calculate the required distance between the two receiving antennas to obtain uncorrelated signals. The results provide the base for the optimum design of the space diversity system.