X-band all-waveguide radial combiner for high power applications

The development of a 12-way X-band all-waveguide radial divider/combiner is presented. The radial combiner is comprised of three parts: a center feed, a radial line, and peripheral waveguide ports. The center feed is comprised of two sections: a rectangular waveguide section and a mode transducer section. The latter is a circular waveguide fed by four-way in-phase combiner to convert the rectangular waveguide TE
₁₀
mode to a TE
₁₀
circular waveguide mode for in-phase feeding of all peripheral ports. For design evaluation, the 12-way combiner was built and tested but also two back-to-back test fixtures, one for the mode transducer and the second for the radial combiner were fabricated and tested as well. The measured insertion loss and phase imbalance of the combiner over a 10% operating bandwidth are less than 0.35 dB and ±5°, respectively. The structure is suitable for high power and should handle few kilowatts.