U-style rotary joint with E01 mode for millimeter waves

This paper describes an improved design of the well-known u-style waveguide rotary joint in millimeter band. It contains H₁₀-to-E₀₁ mode converter by way of a right-angle E-plane junction (RAJ) between a rectangular waveguide and a circular waveguide. A simple for fabrication structure of the RAJ mode converter was proposed, and optimized to provide "conjugate matching" method for the rotary joint. A design procedure was developed. Computer simulation of the mode converter and the rotary joint exhibited excellent performance. The return loss < -25/-35 dB (in 10/6 % band), WOW <0.02/0.002 dB (10/6 %). Testing of the rotary joint, fabricated in Ka band, confirmed simulation results.