The Nature of D-region Scattering of Vertical Incidence Radio Waves. II. Experimental Observations Using Spaced Antenna Reception

Abstract

Statistical properties of the ground diffraction pattern formed by ionospherically reflected radio waves are used to examine models of the angular spectra of reflections from the ionospheric D-region. In the daytime two distinct height regions characterized by differing reflection mechanisms are identified within the D-region. Below 85 km the angular spectrum of reflected waves frequently contains coherent components, whereas a spectrum of incoherent or randomly phased components is characteristic of reflections from the region above 85 km. There is evidence which suggests the presence on many occasions of isolated moving reflectors in the reflecting 'ionospheric screen' . . Both the mean angular spread and the fading speed of waves partially reflected from the D-region show an increase with increasing height of reflection.