Filter Characteristics of Radial Waveguides Coupled by Annular Slots

Using a boundary value treatment, a method is established which gives the internal fields of two coupled radial waveguides. The coupling is achieved by an array of annular slots on the common boundary. It is shown that, in general, higher order modes have significant effect on the solution, for a precise evaluation of the field their contribution must also be included. The possible application of the method for the design of microwave filters with band-pass characteristics is also discussed.