Rotary joint saves space in Ka-band SOTM applications

February 20, 2014 // By Jean-Pierre Joosting
Link Microtek has expanded its range of rotary joints with a compact dual-channel coaxial model that has been specifically designed for use in low-profile Ka-band satellite-on-the-move (SOTM) terminals in either military or commercial applications.

Manufactured at Link Microtek’s premises in Basingstoke, UK, the AMCORJD-Ka rotary joint features a central K-type coaxial channel for transmissions in the 27.5 to 31.0 GHz range, together with an outer DC to 3 GHz SMA coaxial channel for L-band receive signals.

Microwave performance is excellent, with the transmit channel offering an average power rating of 20 W, a VSWR of 1.5:1 and a maximum insertion loss of 1.0 dB. The receive channel can handle an average power of 1 W, and its VSWR and maximum insertion loss are 1.5:1 and 0.25 dB respectively. Isolation between the two channels is a minimum of 50 dB.

The device has been successfully tested with currents as high as 2 A at 24 V, which means that DC can be fed down the outer channel to drive not only the terminal’s LNB but also the motors that enable the antenna to track a satellite while the host vehicle is moving.

Fabricated in aluminium with an Iridite finish, the rotary joint has a body diameter of 31.75 mm and a length of just 37.72 mm excluding connectors. It incorporates a 50.45 mm-diameter flange as standard and can also be supplied with an integral slip-ring assembly if required.

Other outline configurations and sizes are available on request, tailored to suit specific antenna requirements, while for applications where a higher power-handling capability is needed, the device can be specified with a waveguide transmit channel instead of a coaxial connector.