<1>¿¿The problem of wave propagation in a two-dimensional waveguide with vertical absolutely thin barrier and ideally conducting walls is solved in the paper. This is a model approximating the radio wave propagation in the Earth-ionosphere waveguide. The main attention in the model is drawn to the influence of irregularities of the Earth surface including the influence of singular points of an angular type. The presence of the smooth irregularity of the upper wall, i.e., ionosphere, is also taken into account. Two methods of the solution are used: the method of semi-inversion developed by the authors and the method of quasi-static Green function. Using these methods, the diffraction of the field of a dipole at the vertical barrier in a waveguide with curved upper wall and in a waveguide with plain upper wall is calculated. On the basis of the obtained solutions a conclusion is drawn on the influence of ionospheric disturbances on the field.