Optimum antenna height for ionospheric scatter propagation

Radiation patterns of elevated antennas over spherical earth for scatter propagation in the lower ionosphere incorporating refraction, parallax, spherical divergence, and tropospheric defocusing have been used to compute the height gain function resulting from raising and lowering symmetric transmitting and receiving antennas for a fixed path length. This height gain function shows that a broad range of lower antenna heights has a gain over that antenna height computed with the same model which places the maximum of the first lobe at the path midpoint. The maximum of this function is defined as the optimum antenna height.