The monograph is devoted to the theoretical study of a number of problems of electromagnetic wave propagation in the Earth-ionosphere waveguide channel and in the ionosphere .. The solution of the basic problem of the propagation of radio waves excited by a vertical electric dipole in an isotropic regular waveguide with an arbitrary dependence of the properties of the Earth and the ionosphere on the radial coordinate is constructed in the form of a series of normal and a series of repeatedly reflected waves. The results of the work can be used to predict fields for radio communication and radio navigation tasks. The book is intended for specialists in the field of radiophysics, geophysics, radio communication and radio navigation. It can also be used as a teaching aid for high school radiophysicist students.