Analysis and design of Coplanar Waveguide-to-Rectangular Waveguide transition with FDTD method

A broadband coplanar waveguide-to-rectangular waveguide transition is proposed in this paper. The transition consists of a very thin metal ridge, with the shape like a square of cosine curve, located longitudinally on the bottom broadwall of a rectangular waveguide. The ridge guides the power to a slot of triangle cut in the center of the top broadwall of the rectangular waveguide. This structure can result in a smooth field transition between 70 GHz and 120 GHz. The simulation result is achieved by FDTD method, and the result shows that the insertion loss is very low in the transition. This transition is very useful in various applications, such as mixer, multiplier and so on. Furthermore, some conclusions illustrated in this paper can be used to design the transition in many different frequency ranges.