50-Way W-Band All Waveguide Radial Combiner Design

Abstract

This letter presents a novel and challenging design of a 50-way all-waveguide W-band radial combiner, utilizing WR10 ports for all connections. The novelty lies in its pioneering design and implementation of the radial combiner structure, while the challenges stem from the complexities associated with high-frequency design, manufacturing precision, and the integration of multiple waveguide sections. The design begins with a radial combiner featuring rectangular waveguide peripheral ports and a circular waveguide intermediate port operating in the TE₀₁ mode, which is particularly advantageous due to its low loss, attributed to its field distribution with minimal surface current density. A mode transducer is designed to convert the intermediate circular waveguide TE₀₁ mode to the dominant TE₁₀ mode in the WR10 rectangular waveguide. This transducer is integrated with the radial combiner to produce a standard WR10 waveguide output. The design follows a modular approach, dividing the process into separate optimally designed blocks, which are then integrated to form the final structure. Mechanical considerations are crucial at such high frequencies, and all features, such as matching disks and bifurcations, are designed to require only simple mechanical tooling. The design is thoroughly discussed, and an experimental prototype was fabricated and tested, demonstrating good performance without the need for tuning.