A Rotary Joint for Two Microwave Transmission Channels of the Same Frequency Band

This paper describes a rotary joint for two microwave transmission channels of the same frequency band. It consists of two pairs of rectangular waveguide terminals, a circular waveguide which transmits both channels, and coupling elements between the rectangular waveguide terminals and the circular waveguide which convert the rectangular H₁₀ mode into the circular H₀₁ and E₀₁ modes. If pure H₀₁ and E₀₁ modes can be excited, perfect separation of the channels as well as constant amplitudes and phases can be obtained when the joint rotates. While the conversion into the circular E₀₁ mode is performed by a conventional method, a new method had to be developed for the conversion of the rectangular H₁₀ into the circular H₀₁ mode.