TECHNOLOGY FEATURE – MILLIMETRE WAVES IN DEFENCE
23 Jan 09. Since they were first harnessed, microwaves have been used for defence. Essentially radio waves at shorter wavelengths, microwaves allow higher capacity and more secure communication links. Microwaves are also fundamental to high resolution for radars of all kinds. Now, the demands of 21st century deployments – such as sharing of huge amounts of video, sound, and location information – are driving the use of higher frequency millimetre waves (MMWs) for threat detection, communications, and other novel applications.
As the name implies, MMWs are part of the natural electromagnetic spectrum with a wavelength of a millimetre or less. Like infrared, millimetre waves emitted and reflected by objects are used to form images, but – like microwaves – millimetre waves are able to pass through mist, fog, and clouds of dust. So MMW imaging systems can allow pilots to land helicopters and other aircraft safely in “brownout” conditions, by seeing through the dust cloud that is impenetrable to infrared and visible light. Radar imaging systems that transmit and receive MMWs, as well as passive imagers that only receive ambient MMWs are undergoing “brownout” flight trials in the USA this year.
Millimetre waves also pass through many types of clothing, so MMWs are already being deployed to detect weapons and explosives concealed under people’s clothing at a range of up to 20 metres. Defence applications are obvious and MMW systems are already deployed at checkpoints and site perimeters in several conflict zones today. MMWs also allow a higher capacity communications than conventional microwave radio links. Even commercially available MMW radios can transmit and receive more than 1 Gigabit per second in both directions simultaneously (full-duplex). With military operations today sharing vast amounts of information – audio and video from numerous sources – modern forces are already turning to MMW radios to enhance command and control functions with provide live feedback.
With the increasing need to use MMWs to solve current and future problems in the battlespace, what are the barriers? MMW technology has been expensive and difficult to build. Conventional MMW equipment includes large and heavy metal modules milled to a high tolerance, assembled with a very precision.
Now an innovative technology is transforming the way MMW modules and systems are
constructed and manufactured, enabling substantial reductions in cost, size, and weight. MMIC Solutions (MMICS) has extended microwave circuit board techniques to frequencies of 100GHz and more, which now enables MMW modules to be constructed in high volume from circuit boards, rather than milled metal.
Based on original technology licensed from UK defence technology specialists QinetiQ MMICS has developed MMW modules and sub-systems constructed from circuit board, at lower weight, smaller size, and considerably lower costs. MMICS is already supplying 100GHz receivers to manufacturers of people screening equipment for weapon and IED detection, and transceiver modules to reduce the size and weight of MMW radios. MMICS is actively seeking commercial partnerships companies working at MMW in defence markets.