RESUMO

Interest to the Schumann resonance phenomenon is explained by its availability to investigating the lower ionosphere characteristics, while the measurements of these by the direct methods is extremely difficult: the satellites fly at higher heights and the balloons drift at lower altitude. The phenomenon itself arises due to electromagnetic waves of the extremely low frequencies (ELF) that travel around the globe, and the global thunderstorm activity is the source of these waves. When solving the inverse problems, one must have the most adequate mathematical model of the phenomenon combined with the possibility of matching the experimental data by varying the model parameters in the theoretical description. The paper presents the rigorous methods of the ELF fields computations in the regular isotropic Earth-ionosphere waveguide with an emphasis on the power spectra of the vertical electric and horizontal magnetic field components.