Rectangular waveguide to coplanar stripline transition based on a unilateral finline

In this paper we present a wideband rectangular waveguide to coplanar stripline (WG-to-CPS) transition that spans the frequency range 52-89 GHz. The transition has a relative bandwidth of about 52% with respect to 15 dB return loss and an insertion loss in the range of 0.3-1 dB. The transition is based on a unilateral finline and it can be employed in other frequency bands as well. The transition converts the TE₁₀ dominant mode to a differential CPS mode and has a negligible coupling to the common mode. Several samples were fabricated and measured over the V-band and W-band. The comparison between simulation and measurement results demonstrates a good agreement.