Results of the experimental studies of features of HF signals propagation during the period of geomagnetic disturbances at oblique sounding paths in the Eurasian longitudinal sector from England to Magadan are presented. Joint analysis of the vertical and oblique sounding of the ionosphere and satellite data showed that appearance of additional signals during magnetic disturbances can be due to the refraction of radio waves in the region of the auroral oval and the main ionosphere trough and also to the scatter on small-scale field-aligned irregularities in the vicinity of the equatorial boundary of the auroral oval. On the basis of calculations and comparison to the experimental data of the oblique sounding of the midlatitude ionosphere, the side spread signals recorded at Inskip (England) to Rostov on Don path are identified as signals scattered at small-scale field-aligned irregularities, their location positioning to the southern boundary of the auroral oval. The perspective of use of the Russian and global network of linearly frequency modulated ionosondes for studying the dynamics of the midlatitude ionospheric trough and auroral oval in the Eurasian longitudinal sector poorly equipped by observational means during magnetic disturbances is described.