Broadband Coaxial-to-Rectangular Waveguide Transition

This paper presents a wideband transition from WR510 waveguide to a coaxial 50 $\Omega$ port for a frequency range of 1.3 to 1.9 GHz. The proposed transition is designed to be simple in structure, easy to fabricate, and capable of withstanding multiple cryogenic thermal cycles. To achieve impedance matching, the transition includes a four steps ridge and modifications to the inside pin of the coaxial feed. The simulation results show a reflection coefficient better than −30dB and an insertion loss of less than 0.04 dB for the entire bandwidth in simulation.