On conditions for the solvability of the problem of the excitation of a radio waveguide. (Q1432190)

From the text: The excitation of a radio waveguide is the subject of many studies. At the same time, a mathematically rigorous solution to the problem has only been obtained for a hollow waveguide. In the case of a layered radio waveguide with radially varying characteristics, substantial progress was made in [\textit{P. E. Krasnushkin} and \textit{E. I. Moiseev}, Dokl. Akad. Nauk SSSR 264, No.~5, 1123--1127 (1982)]. This paper deals with the solvability of the waveguide excitation problem in which the permittivity and permeability tensors vary arbitrarily through the waveguide cross section.