HF guidance in the vicinity of F layer maximum during ionospheric disturbances

In the regular ionosphere the main characteristics of short wave propagation are described by the geometric-optic approach and have been studied sufficiently well. The existence of irregularities and disturbances of different forms complicates the propagation picture determining the scattering and diffraction effects. Despite widespread investigations of ionosphere irregular structure and its influence on radioelectronic systems the role of irregularities in ionospheric propagation has not yet been established fully. In the report experiments on oblique chirp sounding of the ionosphere, where the guidance effect of the Pedersen mode in the disturbed ionosphere was discovered, are presented. A theoretical explanation of the observed phenomenon is given and opportunities for the use of this effect for diagnostics of irregular structure in the ionosphere are also discussed. (4 pages)