Effect of lower ionosphere on the propagation of VLF waves at low latitudes

Full wave technique is employed to determined the Budden's reflection coefficients and polarization for VLF waves of frequency 5 kHz propagating in the lower region of the ionosphere at low latitudes. The results are then utilized to determine the propagation losses suffered by the waves in the ionosphere and at different hops of propagation in the earth-ionosphere waveguide. The daytime losses are found to be much higher than nighttime losses. By utilizing the nighttime losses, the possibility of earth-ionosphere waveguide mode propagation of VLF emissions observed at two low latitude ground stations of Moshiri and Hiraiso is examined.