Design considerations for obtaining a HE11-mode in a circular waveguide coated with dielectromagnetic material

The propagation of hybrid modes in a circular waveguide coated with dielectromagnetic material is analysed rigorously in the most general case. When applying boundary conditions to the solutions of the wave equation in the air and dielectromagnetic material regions, there is obtained a characteristic equation from which the radial wave numbers and the propagation constants of different modes can be determined numerically. Special attention is devoted to the design considerations for obtaining the HE₁₁-mode with a thin coating of dielectromagnetic material. One of the objectives of the present study is to clarify the controversy in the literature regarding the importance of the losses of the material for obtaining the HE₁₁-mode (Wang et al., 1990)