Antipodal fin-line waveguide to substrate integrated waveguide transition

Presented in this paper is a simple and robust transition of substrate integrated waveguide (SIW) to rectangular waveguide. Based on a tapered fin-line, this transition is designed for dielectric substrate having a relative permittivity higher than 4. It is fabricated using a standard printed circuit board (PCB) process and inserted in the waveguide without modification to the waveguide dimensions. The robustness of the transition with reference to the relative position error is studied showing excellent stability. Measurement results of a back-to-back transition show excellent performance in a bandwidth of 6% (33-35 GHz) with less than 1 dB of insertion loss and a return loss of better than 15 dB. This low loss and small size transition can be used in the development of microwave and millimeter wave circuits.