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Decomposition work of Loran-C resultant waves propagating in the Earth-ionosphere waveguide is concentrated on in this article. Resultant waves of different Earth–ionosphere models are predicted by the FDTD method first. The inverse fast Fourier transform (IFFT) spectral-division technique combined with a filtering process is employed to estimate the delays of different wave-propagation modes in the resultant waves, whereas the amplitudes are solved with the least-square method. Finally, accurate field strengths and delays of different modes (ground waves and skywaves of diverse hops) are obtained, which are important for Loran-C receivers to optimize their performances. [ABSTRACT FROM AUTHOR]

One-hop sky-wave signals in the Earth–ionosphere waveguide are studied based on the traditional wave-hop theory and the finite-difference time-domain (FDTD) method. Field-strength variations of 100 kHz one-hop sky waves are given under three different 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 time domain, the narrowband Loran-C signals are employed in the FDTD method. Compared to the results of wave-hop theory, field-strength variations of low-frequency one-hop sky waves are better characterized by the FDTD method as the waves propagate in an irregular Earth–ionosphere waveguide. [ABSTRACT FROM AUTHOR]