Radiation modes and step discontinuities in dielectric rib waveguide

The continuum spectrum of the rib waveguide is introduced using a method that ensures orthonormality and completeness of the spectrum. A relatively simple approximation of this continuum is obtained. The complete spectrum of the rib waveguide is applied to the abrupt step discontinuity in the E-plane of the rib guide under LSE polarization and to the abrupt termination problem, including radiative effects.