Lined Waveguide*

The existing approximate analysis of wave propagation in lined waveguide is, under practical conditions, limited to linings thinner than 0.025 per cent of the waveguide diameter. A more exact analysis is presented here for the straight and curved waveguide and for all practical linings. In the case of anisotropic or sandwiched linings, the boundary value problem is formulated using wall impedances. The single isotropic lining is taken as an example to prove this formulation useful for typical cases. The exact analysis shows that neither the thickness nor the permittivity of the lining can increase the phase difference between TM11and TE01beyond a certain limit. The curvature coupling between these two waves is enhanced slightly by the lining.