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A waveguide rotary joint is used in microwave communications to connect two different types of RF waveguides .. microwave. microwave. Radio frequency. waveguide. waveguide. Because coaxial parts are symmetrical in ø direction , free rotation without performance degradation is accomplished .. coaxial. coaxial. symmetrical. symmetrical. In the rotating part , electrical continuity is achieved by λ  /  4-chokes eliminating metal contacts .. electrical continuity. electrical continuity. The Rotary Joints can have both waveguide ports at a right angle to the rotational axis , `` U-style '' , one waveguide port at a right angle and one in line , `` L-style '' or both waveguide ports in line .. waveguide. waveguide. `` I-style '' .. Waveguide Rotary Joint modules are available for all frequency bands .