Highly Efficient Technique for the Full-Wave Analysis of Circular Waveguide Filters Including Off-Centered Irises

A rigorous method for the full-wave analysis and design of waveguide filters implemented in circular waveguide technology, and including offcentered circular irises, is presented. The implemented tool is based on an integral equation technique, which provides a full-wave representation of the elementary blocks of the analyzed components in terms of generalized impedance matrices. With the aim of improving the efficiency of the developed tool, the radial variation of the modal solutions of the circular waveguides has been expressed in terms of sinusoidal functions, thus avoiding the use of the more cumbersome Bessel’s functions employed in the classical formulation. Furthermore, line integrals have been used (instead of surface integrals) to compute the modal coupling coefficients of the planar waveguide junctions involved in the considered filters, thus drastically reducing the CPU effort related to the implemented tool. New designs concerning band-pass filters including off-centered circular irises are also provided. The obtained results show that the relative position of the considered circular irises can be considered as a new design parameter with a noteworthy influence on the electrical response of the investigated components. The accuracy of the proposed method has been successfully validated by comparing the obtained results with data extracted from both the technical literature and a commercial software based on the finite-element method.