The Effect of Random Characteristics of Ionosphere on the Propagation of ELoran Sky Waves

In this study, the effect of random characteristics of the ionosphere on the enhanced Loran (eLoran) sky-wave signal was analyzed. First, the bilinear transform stochastic finite-difference time-domain (S-BT-FDTD) method in layered half-space isotropic plasma is derived, and the correctness of the calculation of the mean value and standard deviation of the field components of the eLoran sky-wave signal is verified. Second, the mean value and standard deviation of the amplitude and time delay of the eLoran sky-wave signal were analyzed by combining the International Reference Ionosphere, pseudo-1-D BT-FDTD method, and Monte Carlo method. The simulation results show that the mean value of the amplitude of the reflection coefficient amplitude (RA) in the eLoran signal bandwidth remains unchanged. The larger the standard deviation of the electron density, the larger is the standard deviation of RA. The standard deviation of RA during the day is greater than that at night. The mean value of the time delay remains unchanged, and the standard deviation of the time delay is related to the way the electron density varies randomly. When the incident angle increases, the RA increases, the standard deviation of RA decreases, the time delay decreases, the standard deviation of the time delay decreases, and the signal becomes more stable.