Solution of an open region problem as a limiting case of a closed region problem

Starting from the solution of the bifurcated parallel plate waveguide, the paper derives the solution of an open ended parallel plate waveguide radiating into space. This is achieved by approaching the limit as the transverse dimension of the large guide becomes indefinitely large. It is shown that the expression for the reflection coefficient in the parallel plate waveguide obtained in this manner is the same as that derived by Marcuvitz, Noble, etc., who use the Wiener-Hopf technique. Application of this procedure to other problems, such as surface wave launching on a dielectric or plasma slab, is suggested.