Study on Time Delay Characteristics of Low Frequency One-hop Sky Waves in the Isotropic Ionosphere

Abstract

Accurate prediction of low-frequency sky-wave has significance for the lower ionosphere detection and remote navigation timing. The characteristics of sky-wave propagation time delay in the Earth-ionosphere waveguide are studied in this paper based on the traditional wave-hop theory and FDTD method. Time delay variations of 100 kHz one-hop sky waves are given under homogeneous/exponentially graded isotropic ionosphere waveguide models. The great-circle distance between the transmitter and the receiver is within 200 km. Together with a sky- and ground-wave separation technique in the time domain, the narrow-band Loran-C signals are employed in two methods. Compared to the results of wave-hop theory, the method in this paper has higher calculation accuracy by considering the influence of irregular earth and inhomogeneous distribution of ionospheric day-night parameters at the same time.