Ku Band Rotary Joint Design for SNG Vehicles

Abstract

A wideband I-type rectangular waveguide rotary joint (RJ) is designed, simulated and built. It has an excel- lent performance over the whole Ku Band (10.7-14.5 GHz) where the return loss is less than -23 dB at its highest and the insertion loss is below 0.4 dB. The rotary joint is specifically designed for satellite news gathering (SNG) vehicles provid- ing elevation and azimuthal movement to the antenna and matching polarization when it is needed at the feed. It can also be used in other high power microwave applications, where rotation ability of the antenna is a must during the transmission such as radars. tary joints are required to turn 360 around, providing low loss without any interruption during the transmission. Ku- band rotary joints become significant especially in SNG ve- hicles where usually three dierent Rotary joints are needed in each system. Two of them are used to change azimuth and elevation angles and another one is used for polarization cor- rection. Although some applications use flexible waveguides for polarization correction, this causes unusual loss in the system especially after normal wear and tear. The joints for elevation and azimuth control must perform over the transmit frequency band of 13.75 to 14.5 GHz. The one for polariza- tioncorrectionshouldcoverthewholeKu-Band. Commonly, Ku band Rotary joints are designed for transmit band, 13.75 to14.5GHznotingthat10.7to12.75GHzisthereceiveband for Ku band applications. In this work, the rotary joing cov- ers the whole Ku-Band and mechanically constructed in such a way that it could be used as a joint for all three purposes.