A broadband circular TE11- to TE01-mode converter using stepped waveguide technique

This paper introduces a broadband and compact circular TE₁₁- to TE₀₁-mode converter, realized in stepped waveguide technique and therefore easy to manufacture with standard mortising machines. The concept is presented exemplary for a conversion in a frequency range from 23 GHz to 28 GHz. Hence, a bandwidth of approximately 20 % of the center frequency can be achieved. For the development of an optimized converter design, 3D electromagnetic field simulations are performed within CST Microwave Studio 2013. The simulations include realistic production process parameters, like fillets or tolerances, and show a good return loss of at least 17 dB, while the insertion loss is below 0.1 dB. Compared to measurements of a first prototype in back-to-back assembly, the measurement results validate the expected excellent converter behaviour. Hence, the suitability of the presented converter design is proven and the feasibility is demonstrated.