What is Diffraction
Diffraction happens at the edge of an impenetrable body that is large compared to the wavelength of the radio wave. The edge in effect become a source and waves radiate in dissimilar directions from the edge, allowing a beam to bend around an obstacle. If the size of an obstacle is on the order of the wavelength of the signal or less, scattering happens. An incoming signal is scattered into various weaker outgoing signals in unpredictable directions.