Abstract
An arbitrary shaped iris in rectangular waveguideis investigated using FEM-CDMA with triangularprism elements in this paper. The volume of irisis subdivided into a relatively small number of triangular prism elements and FEM is used to formulate the field distribution. On the other hand, the fields in the waveguide region are represented by BIM derived from the waveguide Green's function and boundary conditions. The proposed method is verified through the design and experiment for the circular iris filter using WR-90 waveguide.