Dual-channel Ku-band rotary joint for radar applications

While microwave rotary joints of this type are usually designed with a high-frequency transmit channel and a lower-frequency L-band receive channel, the new device features two channels operating in the Ku band. Minimising crosstalk is therefore a critical consideration, and the rotary joint achieves an impressive 50dB minimum isolation between the channels with typical figures being better than 70dB.

The Ku-band receive channel allows designers of satellite-on-the-move stabilised antenna platforms to eliminate frequency conversion hardware from the rotating side of the assembly, making for a simpler and more compact antenna design. In addition, the device’s two-channel non-contacting design means it can provide the long life with continuous rotation that is required for use in compact radar antennas. 

In terms of microwave performance, the central transmit channel delivers a VSWR of 1.3:1, an insertion loss of 0.3dB and power rating of 20W CW, while the outer receive channel achieves a VSWR of 1.35:1, insertion loss of 0.5dB and a power rating of 10W CW.

The internal design of the AMCORJD-2KU is based on techniques used in Link Microtek’s large, complex S-band rotary joints, which are typically deployed in air-traffic control, weather forecasting and shipborne applications. The miniaturisation involved in this transfer of technology was a major developmental challenge as the new device measures only 63.5x37.2mm, excluding its four SMA female connectors, whereas the S-band rotary joints can be in excess of a metre in length. 

Designed and manufactured at Link’s premises in Basingstoke, the AMCORJD-2KU is fabricated from lightweight aluminium with a sealing rating of IP64 to protect it from the ingress of moisture and dust. It has an operating temperature range of -40 to 55°C and is specified with a ten year lifetime of continuous rotation.