Focusing Effects in Spherical Earth Radio Propagation

Abstract

THE flat earth scattering theory1 which explained many of the observed effects in relatively long-distance propagation of short radio waves has been extended to cover propagation around a spherical earth. The resulting formulae may be expressed as here, using a co-ordinate system in which the transmitter is located at a pole; Λ is the co-latitude of the receiver, θ is the longitude of the receiver measured from the longitude of the direction of the maximum of the transmitted beam. The power polar diagram of the transmitter is assumed to be of the form exp(− Bθ2). The distribution of received power in the direction ξ measured from the great circle direction between the receiver and the transmitter is then of the form: where n = number of equal steps (half-hops) between the transmitter and the receiver, each of angular length λ. A = average ionospheric scattering factor obtained from a scattering function of the form exp(− Aξ2).