Study of Loran-C One-Hop Sky-Wave Fields at Different Altitudes Above the Ground

To expand the space applications of low-frequency sky-wave signals, Loran-C electromagnetic fields at low and high altitudes in the earth–ionosphere waveguide are studied in this letter. In order to consider the influence of the earth's surface on one-hop sky-wave fields at different altitudes, the wave-hop theory that used for field predictions on the ground is improved, and the wave-hop equation based on the frequency domain is further transformed into the time domain. Then, the proposed approach is applied to calculate the sky-wave fields at the altitudes 0–50 km under given earth–ionosphere models. The accuracy and efficiency of the method are verified by comparison to the finite-difference time-domain method.