Design and simulation of transition waveguide to connect vircator to mode converter

A transition waveguide with corrugations is proposed to connect Virtual Cathode Oscillator (Vircator) to mode converter. The Transition is compact in size and overmoded transmission is possible with high efficiency. Such transition is useful for high power microwave sources, where output consists of TM₀₁ and TE₁₁ modes, and both modes need to be transmitted. The proposed waveguide is designed for S-band operation and connects 18 cm diameter Vircator output to 9 cm diameter input of the mode converter. The cosine profile results in smallest length of the waveguide with more than 90% transmission efficiency of TM₀₁ and TE₁₁ modes.