Peculiarities of decameter radio wave propagation over high-latitude paths using data of LFM-ionosondes network

In this work we study peculiarities of high frequency signals propagation over network of Linear Frequency Modulated (LFM) ionosondes located above 60N. The transmitters are located in Magadan (60.1N, 150.7E), Dikson (73.5N, 80.7E), Lovozero (68N, 35E), Amderma (69.6N, 60.2E), Salekhard (66.5N, 66.7E), Pevek (70N, 170.9E), the receiver is in Norilsk (69.4N, 88.4E). For Magadan-Norilsk and Pevek-Norilsk paths comparison between maximum observed frequencies reflected from F2-region of ionosphere and maximum usable frequencies calculated using program on the base of waveguide approach and International Reference Ionosphere has been carried out. By means of morphological analysis we consider intervals when HF signals are scattered from small-scale inhomogeneities. We consider also registration of abnormal signal modes reflected from the F region of the ionosphere. Such peculiarities of decameter radio wave propagation have not been taken into consideration by the standard long-term models of ionosphere at the present time.