Loss of radio signals in the ionospheric D layer in presence of the Sun, including the day-night transition hour are the challenging problems when planning a radio communications network and predicting propagation of radio signal. An overview of the electron density of the different layers of the ionosphere and the mechanism of radio waves propagation have highlighted first. Our study suggests that the noise powers in the days of perturbed meteorological condition is smaller than those in the days associated with the solar bursts. A comparison of the received signal during daytime in presence of the Sun and after sunset is done for different occasions in the ELF/VLF bands which show that there is a clear indication of signal attenuation during daytime.

Keywords: radio signals; ionosphere; radio communications; radio wave propagation; solar burs
View Full Paper