Volume 126 (2006) Issue 11 Pages 1173-1176
This paper analyzes propagation of wideband electromagnetic (EM) wave in the ionosphere. The influence of total electron contents (TEC) of the ionosphere on the propagation of EM wave is investigated numerically. Our attention is paid to very high frequency (VHF) band, which is dominant frequency band of EM waves emitted from lightning discharges. A one-dimensional model of the ionosphere is considered for simplicity. The ionosphere is treated as an anisotropic and dispersive medium. Particularly, the altitude distribution of electron density is taken into consideration. Variation of pulse width and difference in the arrival time between each frequency component due to the dispersion in the ionosphere are revealed. For our numerical investigation, group delay of the EM wave is found to be dependent on the altitude distribution of electron density, especially when the peak electron density is the order of 1012m-3 or more.