R&D Report 1968-30 : Propagation over rounded hills K. Hacking
Several features of the diffraction of electromagnetic waves by large obstacles are examined both theoretically and by optical experiments using a laser source and idealized models. The underlying purpose of the work was to establish and verify, where possible, working methods for estimating the field strength in the shadows of rounded hills. The emphasis throughout is for the special conditions which arise in UHF broadcasting, where ordinary terrain has a near-dielectric behaviour and its surface becomes effectively rough. Hill curvature in the direction of propagation is shown to be an important factor. An attempt is made to deal with hill crests whose surfaces are randomly rough and with those of irregular shape.