RT Journal Article
SR Electronic
T1 Degenerate modes in the Earth-ionosphere waveguide
JF Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences
JO Proc R Soc Lond A Math Phys Sci
FD The Royal Society
SP 175
OP 190
DO 10.1098/rspa.1975.0019
VO 342
IS 1629
A1
A1
YR 1975
UL http://rspa.royalsocietypublishing.org/content/342/1629/175.abstract
AB In a stratified wave guiding system it is often possible to adjust parameters such as the wave frequency, or some dimension of the guide, so that the complex propagation constants of two modes become equal. These modes are then said to be degenerate. Some examples occur in the waveguide formed by the Earthâ€™s surface and the ionosphere. It is shown that, for conditions near degeneracy, there must be an ambiguity in the mode numbering system. For a given source the two modes may be excited with large amplitudes but in antiphase so that they behave like a single composite mode whose excitation is not large. A degenerate mode is selforthogonal, and some consequences of this are discussed. A degenerate mode can often be associated with a complex Brewster angle for the reflexion coefficient of the Earthâ€™s surface or of the ionosphere.