Substrate-integrated waveguide circuit analysis and optimisation

This work proposes a technique for the analysis of electrically large substrate-integrated waveguide (SIW) circuits. For this purpose, the circuit is first decomposed into a number of two or multi-port sub-circuits. A commercial full-wave solver is then used to determine the scattering parameters of these sub-circuits with respect to their reference planes, which are also chosen on their connecting SIWs. Using this type of waveguide as the reference waveguide of the sub-circuits enables us to analyse a large variety of SIW circuits. A library of scattering parameters of mostly utilised sub-circuits or components, such as Y-junctions, bends etc., is generated. The overall scattering parameters of the circuit are then evaluated using a proper connection of the scattering parameters of the SIW sub-circuits. The paper also discusses the conditions under which the proposed analysis provides the desired accuracy. With the help of this method, we have analysed and optimised electrically large SIW circuits, such as a four-way power splitter.