K-band substrate integrated waveguide to rectangular waveguide transition

In this paper, a K-band broadband in-line transition from a substrate integrated waveguide (SIW) to a rectangular waveguide (RWG) is proposed. The transition is realized by using a substrate taper inserted into a height-stepped impedance transformer in the RWG region. The transition is designed to cover the 18-26 GHz frequency band, showing a return loss of 20 dB. A back-to-back transition has been fabricated to verify the proposed transition. The measured results show good agreement with the simulation. The results show an insertion loss less than 0.65 dB and a return loss better than 16 dB in the designed frequency band.