Relations Between the Bearing and Elevation Angle
The three quantities of most interest in the study of scintillations are the instantaneous bearing, amplitude and elevation angle. So far this discussion on scintillation has been mainly on the relation between bearing angles and amplitudes ignoring the fact that the incoming wave can also vary in elevation angle. The foregoing thus refers to the characteristics of the projection of the actual wave normal direction on to a horizontal plane. In considering the relationship of elevation angles to amplitudes we would, similarly, be concerned with the projection of the wave-normal direction on to a vertical plane through the mean direction. In both these cases, the simple concept of a two dimensional angular power spectrum is applicable. The relationships between the amplitude and the elevation angle are similar to those obtained between the amplitude and the bearing angle (both in theory and in actual experiment) and will not be discussed in detail. The only difference is that the bearing angles in the above curves are replaced by the elevation angles which are obtained experimentally from measurements of the instantaneous ground wavelength.
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