Substrate-integrated waveguide filter design using mode-matching techniques

Mode-matching techniques are employed for the analysis and design of substrate-integrated waveguide (SIW) filters. Recently developed fabrication techniques based on rectangular-shaped via holes facilitate a straight-forwardly implementable and powerful CAD code. Only two principle discontinuities, dielectric-to-dielectric waveguide and dielectric waveguide to multiple via-hole section, are involved. The basic theory, especially with respect to the treatment of sections with an arbitrary number of via holes, is presented. Design examples include a SIW metal-insert filter, a SIW inductive-iris filter and a SIW dual-mode filter with one transmission zero. Results are validated by comparison with the commercially available field solver CST Microwave Studio.