Compact and Broadband Rectangular Waveguide-to-Circular Waveguide Transition

As rectangular waveguides (RWGs) and circular waveguides (CWGs) possess high power and low loss characteristics, they are commonly used in satellite communications where these characteristics are desired. Furthermore, as the low earth orbit (LEO) satellite communication systems advance, integrating the microwave components of rectangular and circular waveguides becomes essential. To incorporate the RWG component with the CWG component, a miniaturized and wideband rectangular waveguide (RWG)-to-circular waveguide (CWG) transition is required. Therefore, we developed a miniaturized and wideband RWG-to-CWG transition by employing the D-shaped and Y-shaped strips. The transition has a wideband response in that the frequency range of the −15 dB reflection coefficient spans from 9.3 to 11.8 GHz, estimated to be approximately 23.8%. In this frequency span, the transmission coefficient has a value greater than −0.05 dB. In comparison with the RWG-to-CWG transitions using other skills in the literature, the transition can eliminate the mechanical complexity, reduce the circuit size, and enhance the bandwidth. To prove the feasibility of the proposed RWG-to-CWG transition, two RWG-to-CWG transitions are connected in a back-to-back structure, implemented, and measured. The measurement results agree with the simulation results.