There are some who think that an antenna is just a metal rod or, at best, a rotating parabolic reflector. They have clearly missed much of the development work associated with group antennas, a field in which FOI is one of the leading players.
Anyone who looks carefully at a modern aircraft or ship can see that parts of the forest of antennas that used to be visible have now been replaced by smooth antenna surfaces – up to a dozen on an aircraft and perhaps twenty or more on a ship. These flat surfaces, which can measure from 20 x 20 cm up to several metres, are made up of a large number of small antennas working together.
This so-called ‘group antenna’ technology is an area that has seen vigorous growth in recent years.
“New materials such as gallium nitride have allowed greatly increased power levels and made it possible to detect objects at long ranges, while miniaturisation has made it possible to use group antennas on unmanned aircraft, so-called UAVs or drones,” explains Stefan Persson, a research scientist at FOI.
The advantages compared with traditional antenna technology are many. Since a large and heavy parabolic antenna must be turned in order to study several targets, there is a risk that a target of interest may, by then, already have disappeared. A group antenna, on the other hand, can switch between targets and form a new picture in no more than a microsecond. A group antenna can also be used for many different things at the same time – for example radar, communications and electronic warfare.
As for disadvantages, there is really only one: cost. But as more and more users choose group antennas – the United States is currently replacing all its coastal radars – prices will fall.
“Today it is essentially only the military and the aerospace industry that can afford this technology. But soon I expect to see group antennas being adopted increasingly in the shipping world,” says Stefan Persson.
FOI is right at the forefront of group antenna development and has already delivered a number of demonstrators to the Swedish Armed Forces.
“We build and develop such devices ourselves. And in certain areas, such as electronic warfare and radar, our facilities are amongst the best in the world,” adds Stefan Persson.
According to Stefan Persson, smart group antennas will in the future also be finding many new areas of application.
“For example in the transfer of large amounts of data from point to point. Military and defence applications come to mind, but in the civil sector the technology would, for example, allow telecom companies to use group antennas instead if large parabolic antennas. Similarly, distributors of television signals will could transmit 4k (ultra HD) content over the air rather than by fibre optic cable.”