Measurements of the Coherence Ratio of Ionospherically Propagated Radio Waves

Abstract

Phase difference measurements made with an accuracy of 5° between pairs of antennas separated by up to 150 yards in three directions (N, E, and SW) show that radio waves reflected from the ionosphere are generally not sufficiently stable in direction for any particular component to be regarded as being specular in the usual sense. It is concluded that the coherence ratio should be regarded as equal to zero except in very special one‐hop cases. The equipment used for the measurements is described in general form.

Small‐Aperture Measurements of the Shape of the Received Cone of Rays in Long‐Distance Ionospheric Propagation

“…It appears likely that the distributions in the vertical plane are actually made up of several overlapping distributions, thus indicating the existence of discrete groups of rays in the downcoming ensemble. This observation agrees with the conclusion reached by Whale and Boys [1968]. More complicated relations hold if more than one wave is arriving at different elevation angles.…”

“…A previous paper [Whale and Boys, 1968] dem-Copyright ¸ 1969 by the American Geophysical Union. onstrated experimentally that the coherence ratio (the ratio of the power in the specular component to the total power in the scattered components) of any radio wave that has been propagated via the ionosphere may be considered to be near zero if the observation is made by using a phase difference technique; it was concluded that this result is primarily due to the multiplicity of paths that exist between the transmitter and the receiver.…”

Statistical Variations in the Apparent Specular Component of Ionospherically Reflected Radio Waves

“…In a previous paper (Whale and Boys, 1968, hereinafter called paper l) it is shown experimentally that any radio signal which has undergone many reflections from the ionosphere always has a negligibly small specular component. This result arises primarily because of the multiplicity of paths that may exist between any distant transmitter and the receiver.…”