Waveguide Pseudoelliptic Filters Using Slant and Transverse Rectangular Ridge Resonators

This paper presents a novel class of resonators suitable for the design of waveguide pseudoelliptic filters. The basic structure is a rectangular ridge arbitrarily located and oriented within a rectangular waveguide sized to allow the propagation of the fundamental TE₁₀ mode. The ridge has the capability to provide both a reflection and a transmission zero, thus behaving as a singlet. The coupling coefficients of the resonator can be controlled by varying the position and orientation of the ridge, or by additional elements such as irises or ridge taps. Compact pseudoelliptic filters can be designed by cascading multiple ridges and half a wavelength waveguide sections. A practical design procedure is presented. The experimental results of a fifth-order filter with three resonant ridges validate the proposed approach.