Substrate Integrated Waveguide Two-Mode Coaxial Launcher

—This article presents an innovative single-layer coaxial-to-substrate integrated waveguide (SIW) transition. The novelty consists in the capability to independently launch both the first and second SIW modes in the same structure. First, the electromagnetic performance of two single-mode launchers has been investigated. Parametric analyses show the effect of the substrate height, the position of the coaxial connector, and the geometry of the structure on the frequency response of the transition. Subsequently, two prototypes of the first and second SIW mode launchers were designed, manufactured, and experimentally validated. In the proposed structures, the central conductor of the coaxial feed is directly inserted through the substrate and soldered on the bottom metal plane, ensuring a solution that is simple to fabricate and mechanically robust. Finally, the combination of the two structures led to the design of the SIW two-mode coaxial launcher. The features of the lancher are illustrated and discussed, and a prototype has been realized and measured.