Short-circuit equivalence between rectangular waveguides of regular sidewalls (rectangular waveguide) and sidewalls of cylinders (substrate-integrated rectangular waveguides), plus its extension to cavity

Substrate-integrated rectangular waveguide (SIW) is a rectangular waveguide (RW) with two sidewalls of cylinders (vias) instead of solid walls connecting the solid wall of the top and bottom plates. An equivalence formula between their widths has been derived based on the work by Che et al., 2005 [2005 Asia-Pacific Microwave Conference, Suzhou, China, December 4-7, 2005, pp. 296-299]. The authors have derived the equivalence formula between the locations of the corresponding short circuits by cylinder walls and by the solid wall. An extension of latter is the equivalence between resonance cavities of SIW and RW. Such equivalences are convenient for the design of small waveguides, of millimeter wave, in a multilayer circuit structure, such as the low-temperature co-fired ceramic. Some numerical simulations and experiments have been carried out to demonstrate the validity of the proposed approaches