Half-mode versus folded SIW filters: Modeling and design

Half-mode and folded substrate integrated waveguide (SIW) components allow to reduce the footprint of components and circuits, compared to a standard SIW structure, with limited impact on the performance. In this paper, the two topologies are compared in the design of a compact cavity filter operating at 4.5 GHz. The filters are designed by exploiting the control of the cavity modes, whose resonance frequencies can be adjusted by properly modifying insets in the metal septum. A prototype of a half-mode SIW two-pole filter has been design and fabricated, and its performance is compared with an analogous folded SIW filter that has been recently published.