Propagation conditions of 10 MHz signals along the paths between Rostov and Moscow

Abstract

Abstract To determine the conditions for the propagation of HF signals through the ionosphere along various paths, there are several possibilities: (1) ionograms of vertical sounding, (2) ionograms of oblique sounding between transmission and receiver points, (3) receiving signals from transmitters of exact time at fixed frequencies (here ~10 MHz), (4) using ionospheric models. This paper presents the results of a comprehensive study that implements all these possibilities. They refer to the propagation of HF signals on reciprocal paths between Rostov and Moscow during the period of the lowest solar activity of cycle 24 (April-May 2020). It is shown that the maximum usable frequency (MUF) of propagation through the F2 layer of the ionosphere in the overwhelming majority of cases did not exceed 10 MHz both in the experiment and according to model calculations. The signals were propagated through the Es layer. If earlier it was shown that such a joint experiment allows revealing the presence of traveling ionospheric disturbances, the results of this work emphasize the role of the Es layer.