Propagation Theory Of SLF/ELF Waves In An Anisotropic Earth-ionosphere Waveguide

For the past century,the characteristics of super low frequency(SLF: 30-300Hz)and extremely low frequency(ELF: below 30 Hz)radio waves propagation in the earth-ionosphere waveguide are investigated widely because of its useful properties in applications such as navigation,geographical prospecting,earthquake detection,and so on.In this paper,considering the effects of the ions in the ionosphere,both the multiple-path interference(MPI)and the phase standard deviation are treated analytically.The main research work is briefly introduced as follows:Firstly,considering the effect of electron collision frequency and ion collision frequency,the solution of the model equation is presented for the first time,and then applied to the Schumann effect.Secondly,we derive the phase standard deviation of ELF wave propagation in an anisotropic Earth-ionosphere waveguide analytically.It is found that the locations of maximum phase standard deviations coincide with the locations of minimum electric field amplitude.Moreover,the interference presents evident aggregation at certain heights,and the intensity in the nighttime is larger than the one in the daytime.Finally,the phase standard deviation formula of the horizontal electric dipole is extended to the cross antenna.Then the distribution law of phase standard deviation is analyzed again with respect to propagation direction and geomagnetic declination.It is found that the law of the phase standard deviation distribution under this model consists with that of the horizontal electric dipole.