Combined effects of terrestrial diffraction and ionospheric reflection on medium-frequency sky wave propagation

A theoretical analysis is made on the titled subject as an extension of the classical theory (elaborated by H. Bremmer) of the ionospheric propagation. A physical parameter, which is akin to the conventional convergence or divergence coefficient introduced by Bremmer, is formulated in an approximate integral representation which is applicable at low to negative angles of departure/arrival, and the integral is evaluated by numerical means. Part of the result obtained from this analysis is further applied to the estimation of the interhop polarisation coupling factor, which has been formulated by G.J. Phillips and P. Knight. Striking features emerging from, and the adequacy of, the present analysis are demonstrated with a typical example.