Compact multiple channel rotary joint

Abstract

A multiple channel rotary joint design is described in which the channel components are laid out in a manner to reduce the number of layers of microwave circuitry necessary to provide rotary coupling with the antenna. The reduction of layers in each channel allows room for larger conductors in each channel, providing greater power handling capability. Compactness is also achieved through the use of a novel central extrusion that replaces the usual coaxial input lines, novel choke designs, and a novel stripline configuration that makes dual use of various components and minimizes losses within the joint. The central extrusion provides all the high power inputs, while allowing the passage through its center of a plurality of low power coaxial lines to low power channels residing on top of the high power channels. Cooling of the rotary joint is simplified by keeping the center of the joint stationary, and cooling air is fed through the transmission lines to make this function more efficient. One pair of bearings is used for the entire multiple channel joint rather than using individual channel bearings in order to reduce tolerance buildup and weight. The use of numerically controlled machining in the manufacturing process guarantees channel-to-channel reproducibility and achieves tolerances suitable for high performance chokes.