Application of diffractive-refractive scattering to VHF wave propagation

Diffractive scattering is caused by irregularities whose scale is less than the Fresnel scale. Refractive scattering is caused by irregularities whose scale is greater than the Fresnel scale. Spatial correlation function for the waves scattered by the power law irregularities are formulated. Comparison of spatial correlation function with the irregularity scale is found to be very useful for interplanetary scintillation and ionospheric scintillation. The author indicates that for interplanetary scintillation, the ratio of the pattern scale and irregularity scale varies with solar elongation angle. For several ionospheric scintillation events, it is found that initially and towards the end of the event diffractive scattering dominates. In the middle of the event when scintillation is strong, refractive scattering dominates