Inspec keywords: radiowave propagation; guided electromagnetic wave propagation; ionosphere

Other keywords: phase velocities; path length and the frequency; calculation; sunrise and sunset times; propagation path; day and night waveguide modes; wider range of validity; modal propagation constants; conversion factors; attenuation coefficients; two day modes model; very low frequency signals; propagation parameters; observations; two night modes model

Subjects: Waveguide and cavity theory