Sieganschin, AntonAntonSieganschinTegowski, BartoszBartoszTegowskiKölpin, AlexanderAlexanderKölpinJacob, ArneArneJacob2023-08-102023-08-102023-05-05International journal of microwave and wireless technologies 15 (6): 993-1000 (2023-05-05)https://hdl.handle.net/11420/42560This contribution presents miniaturization techniques for folded circular substrate integrated waveguide (FCSIW) cavity filters. The cavities support dual-mode operation. Two of these cavities are combined to form a fourth-order filter. Two filter designs are implemented. The first one serves as a reference and exhibits good manufacturability. For the second one, the cavity is modified, which leads to 50% more compactness. The designs are experimentally verified with 10 GHz bandpass filters. Even though the achieved level of compactness requires higher technological effort, the measurements validate the miniaturization concept. The out-of-band rejection exceeds 40 dB between 11.2 and 30 GHz for the reference filter and between 11.3 and 33 GHz for the miniaturized one. The implemented components are compared with state-of-the-art filters.en1759-0787202369931000https://creativecommons.org/licenses/by/4.0/MiniaturizationX-bandFilterFolded substrate integrated waveguide (FSIW)substrate integrated waveguide (SIW)PhysicsMathematicsJournal Article10.15480/882.811710.1017/S175907872200121010.15480/882.8117Journal Article