A K-band Wideband Low Insertion Loss SIW-to-Waveguide Transition

This paper presents a K-band wideband SIW-to-waveguide transitions composed of the SIW cavity and the double ridged waveguide, which realized the impedance and field transition. The transition structure includes the double ridge waveguide, SIW cavity and SIW-to-GCPW transmission line. By adjusting the size of SIW cavity metal patch and four steps of ridged waveguide, the broadband matching of transition structure is realized. The simulation and measurement results show that the fabricated transition achieves a wide impedance bandwidth from 18 to 27 GHz with a reflection coefficient below -20 dB. The insertion loss is below 1.2 dB, which can be applied to the millimeter-wave system and radar in K-band.