Ka-band microwave rotary joint is designed for Surrey Satellite antenna
A spaceflight-qualified microwave rotary joint and associated waveguide components as part of a Ka-band antenna pointing mechanism (APM) has been designed and produced for Surrey Satellite Technology, an independent company within Airbus.
Link Microtek, the manufacturer of microwave and RF subsystems and components, has designed and produced the Ka-band APM which is destined for use on low earth orbit (LEO) satellites. It will enable the maximum amount of high data rate information, such as high-resolution images or video, to be transmitted to a ground station as the satellite completes its rapid traverse of the sky. Within the APM, the rotary joint performs the critical function of feeding the RF carrier signal from the static side of the antenna to the rotating side.
The challenging design consisted of rotary joint and waveguide components which had to combine very low loss performance, low weight and long life, while at the same time being able to withstand the extreme physical demands of vacuum, vibration and temperature variation. These factors make the design and manufacture of these parts very challenging, explains Link Microtek.
Surrey Satellite’s APM design includes two Link Microtek rotary joints, one for azimuth and one for elevation and interconnecting waveguides, which are made from aluminium to minimise weight and are crucial to the overall RF performance of the system.
Each rotary joint is of single-channel, non-contacting design covering the frequency band 25.5 to 27.0GHz. Also made from aluminium, the rotary joints feature a WR34 waveguide interface on both ends and a bespoke flange design. The measured RF performance is a very low maximum insertion loss of 0.29dB, a maximum insertion loss WOW of 0.12, maximum VSWR of 1.28:1 and maximum VSWR WOW of 0.13.
According to LinkMicrotek, the development of the new Ka-band APM will significantly enhance SSTL’s data downlink capability, enabling it to support a data throughput of up to 1Gbps for a variety of high-resolution imaging applications.
