Ray tracing calculation correction for wave propagation inside evaporation ducts

A method to adjust the propagation factor given by ray tracing in order to take into account the effects of evaporation ducts is proposed. The effective Earth radius is modified to obtain with ray tracing a propagation factor whose value is close to the one computed by the parabolic equation method (PEM). An equation is obtained and is applied to the problem of low-angle tracking of a radar target in order to verify the effectiveness and the usefulness of the proposed method.