Bandpass Filters Based on L-ridged Rectangular Waveguides

We solve the problem of electrodynamic analysis and synthesis of bandpass filters based on rectangular waveguides with complex L-shaped ridges. Cutoff wave numbers and components of the electromagnetic field were calculated by the partial region method with allowance for the singularity of the electromagnetic field on metal ribs. As a prototype, the model of a cutoff filter and an approximation of its amplitude-frequency characteristic by the Chebyshev polynomials were used. Examples of synthesis of narrow-band filters with inputs based on a rectangular waveguide and an H-waveguide are presented. Advantages of using a novel waveguide with a complex cross section in the filter are considered, including the appearance of a total reflection frequency (antiresonance) in the filter rejection band, which allows one to significantly extend this band and increase the attenuation level in it.