Investigation of a radial, parallel-plate waveguide with an annular slot

A parallel-plate, radial waveguide with an annular slot in its upper plate is excited by a known transverse electromagnetic wave. An integral equation is derived for the electric field in the annular aperture, and this equation is solved numerically. Attention is given to the construction of Green's functions for the waveguide interior as well as for the exterior half space above the guide. Efficient techniques are discussed for evaluating improper integrals and summing infinite series that arise in the numerical solution procedure. The electric field in both narrow and wide slots is determined as a solution of the integral equation, and when the interior and exterior dielectrics are different, the occurrence of surface waves in the slot region is observed. Values for scattering parameters and far-zone radiated fields are presented.