Wideband Rotary Joint Based on Gap Waveguide Technology

This article presents a wideband design of a rotary joint based on groove gap waveguide technology. The proposed design includes two coax-to-groove gap waveguide (GGW) transitions, connected together in a back-to-back arrangement. As the gap waveguide structure does not require electrical connections between different parts, the rotor part is placed on top of the stator with an air gap distance while the wave leakage is suppressed. Therefore, the rotating choke, which is a critical and bulky part in the previous designs, is eliminated. By introducing some matching posts in the structure, a wideband design is achieved with 55% bandwidth covering from 11 to 19.5 GHz, where the insertion loss is lower than 0.28 dB. Some parameter sweeps are presented to investigate the effect of the rotor displacement during rotation. A prototype of the proposed rotary joint was fabricated using CNC milling for verification of the design. The measured results agree well with the simulated ones and prove the excellent performance of the proposed rotary joint.