A W-band transition from coplanar waveguide to rectangular waveguide

This paper presents conversion from coplanar waveguide (CPW) to fundamental rectangular waveguide mode for millimeter-wave applications. The transition is designed using cosine shaped fin to give broadband operation. It provides an efficient solution to in-line integration with optoelectronic devices on lithium niobate for the applications of millimeter-wave to optical signal processing. Optimization of the model is carried out using 3-D finite element method solver HFSS by Ansoft Corporation. Measurements of a fabricated device have yielded return loss below -15 dB and insertion loss about -3.5 dB over full W-band (75-110 GHz).