Use of a high-speed computer for ground-wave calculations

Procedures for calculating the propagation loss between antennas located near the surface of a smooth spherical earth of finite conductivity in the absence of an atmosphere have been known for many years. The increasing availability of high-speed computers suggests that the drudgery of such calculations can be eliminated, and more accurate and voluminous data made available. The equations and graphical aids developed in the past generally are not well adapted for use with computers. This report outlines methods whereby the field strength relative to free space can be calculated for the cases where the ionosphere is neglected and refraction in the troposphere is approximated by assuming an appropriate constant gradient of refractive index. Plane-earth methods are employed to determine the solution for short distances, and the residue series is used under conditions where the surface curvature is important. The input parameters are the horizontal distance, the antenna heights, the equivalent radius of the earth, the wavelength, and the dielectric constant and conductivity of the earth.