Radiation from an open waveguide with reactive walls

An exact solution is obtained for the problem of a radiating parallel plate waveguide when the inside walls are inductively loaded and the outside walls are capacitively loaded. Also, an impedance boundary condition is assumed along the center line of the configuration. The structure serves as a canonical model for two important types of antennas: an inductively loaded horn and a horn-type surface wave launcher. Exact closed-form expressions are computed for quantities of physical interest: the reflection coeffieient at the waveguide mouth, the radiation power pattern, and the power in the radiated surface wave. Various graphs show how the antenna pattern and the launching efficiency vary with the different parameters.