Compact broadband coaxial to rectangular waveguide transition

Coaxial to waveguide transitions play an important role in high frequency systems. The excitation signal to be employed for the calibration of high-power systems and microwave components is typically in the form of standard 50 omega coaxial port. Therefore, it is necessary to provide a transition medium to inject the coaxial signal into the waveguide medium. This article presents a simple yet effective coaxial to waveguide transition. A cone-shaped transition including a cone-shaped impedance match section is proposed. Simulation and measurement results are presented. The insertion loss of better than 10 dB is achieved for the operating bandwidth of 2.2-4.6 GHz, which shows superior performance, considering other transition units. Moreover, the simplicity of the design and structure makes is feasible to be employed for other waveguides. The proposed broadband transition design is suitable to be employed as the feed of broadband horn antennas, as well as the TE mode launcher feed.