Broadening our horizons

Antenna technology being developed in the UK could significantly cut the cost of equipping commercial airliners with broadband satellite data links.

A consortium led by R&D specialist ERA and including Thales Avionics and Chelton aims to produce a satellite antenna system tailor-made for the civil aviation industry within two years.

Airlines are increasingly keen to give passengers the full benefits of broadband satcoms, including access to services such as TV channels, the internet and telephone. Satellite technology would also open the way for full operational links to be maintained with airliners even when they are mid-ocean on a long-haul flight, improving the monitoring of safety systems and allowing aircraft to be tracked more effectively.

A subsidiary of Boeing plans to launch such services early next year. But finding suitable antenna technology has proved a headache for the aerospace industry.

Conventional mechanically steered dish antennas are cheap but create additional drag when fitted to aircraft, leading to high extra fuel costs. The only current alternatives are electronics-based phased-array antennas, which can adopt a low profile on the aircraft by being encased in a static, aerodynamically friendly radome.Phased-array systems are also more efficient at scanning for the best signal and switching automatically between satellites. However, they are very expensive and mainly used in radars and specialist military systems.

The UK research effort is based on a hybrid antenna technology developed by ERA that claims to combine the best features of electronic and mechanically controlled systems. This offers 360-degree scan coverage without the need for electronic phase shifters – the devices in a phase array antenna that allow the direction of its beam to be steered without the need for mechanical repositioning.

Phase-shifters account for a large proportion of the cost of the antenna. Instead, ERA has patented a technology that mechanically modifies the geometry of the antenna’s scanning lines to control the direction of the scan.

The antenna will be housed in a radome, giving it the necessary low profile on the airframe and creating negligible drag.

According to ERA, its technology also commands low manufacturing costs, and has a wide range of other applications to ground-based mobile satellite systems suitable for trains and cars.

The DTI has pledged more than £2m to the research initiative, called Spitfire, as part of its aeronautics research programme.