The role of partial reflections in tropospheric propagation beyond the horizon

Measurements on vhf transmissions in recent years have indicated that field strengths deep in the diffraction region are many orders of magnitude greater than values calculated on a smooth earth diffraction theory, even vii en allowance is made for the refraction produced by the standard atmosphere1 Of the theories advanced to date in explanation of this effect, the machanism of scattering by inhomogeneities resulting from atmospheric turbulence has perhaps been the most successful.2 However, certain discrepancies in wavelength and angle dependence, together with the fact that the abnormal fields apparently exist everywhere at all times, lead one to seek an explanation solely in terms of the model represented by the standard atmosphere.