The degeneracy of modes in a waveguide in the case of an oblique incidence at termination

Budden (1975) has considered degenerated modes in the waveguide earth-ionosphere for the case in which the path of the signal is orthogonally oriented. The dependence of the field of the degenerated modes on the longitudinal coordinate for the considered conditions is described by the Airy function. The present investigation has the objective to provide a description of the field of degenerate modes for a situation in which an oblique orientation exists between the path of wave propagation and the line of termination. The case of oblique incidence in the absence of degeneracy has been solved by Lutchenko (1984). This solution is briefly described, and conditions arising in the presence of degeneracy are pointed out. The field in the waveguide is considered along with the Fourier transform. An operator equation is derived, taking into account Maxwell's equations. The obtained solution is evaluated, and the effects of the degeneracy on the results are discussed.