Metamaterials might be used to create a real-life invisibility cloak, or even a cloak of silence -- some day. The Pentagon is seeking short-term gains by using metamaterials for revolutionary new antennas with obvious commercial spin-offs.
In fact, this is back where metamaterials started, when Prof. Sir John Pendry found that bundles of carbon fiber did not reflect radar in the usual way. Metamaterials gain their special properties because of the way they are structured, rather than their composition. This entails having a structure on the same scale as the wavelengths involved, so a metamaterial to influence light is going to require nano-technology, whereas radio waves and microwaves work on a scale of centimeters so metamaterials to influence them are far more practical in the short term.
Which is why the Air Force has put out a call for "Applied Metamaterials for Antennas." The goal is to demonstrate materials could improve antennas by:
" Beam shaping and steering / lobe control; enhanced center frequency tuning range; enhanced bandwidth; reduction in antenna size/weight/thickness; and enablers for conformal, flexible antenna designs. The overall technical objective of this research is to develop improved metamaterials with low electrical losses and simultaneous control over permittivity and permeability in the 20MHz to 10GHz frequency range. "
What does that mean, in English? Better antennas which give an improved performance for the same size. In particular, this is about conformal antennas which are integrated into a surface -- rather than sticking out from it. These are useful for aircraft and UAVs; metamaterial antennas could provide 'em with better radar and communications.
There is plenty of commercial potential for this technology, too. A metamaterial antenna does not just mean improved radio reception from a smaller aerial. It also means mobile phones which can work from a fainter signal and which less power. The same goes for Wi-Fi, Bluetooth and other wireless devices.The future urban landscape might benefit when all TV aerials, satellite dishes and mobile phone masts are replaced with conformal antennas.
The Air Force's call for proposals on metamaterial development is for a three-year program which will also investigate optical metamaterials. No invisibility cloaks, alas. But they are considering "optical / IR beam steering, compact optical systems, mirrors, optical circuitry, interconnects, filters and limiter applications."
This kind of technology could lead to a drastic increase in the amount of data you can fit optical media like DVDs ; a flat metamaterial 'lens' can beat the diffraction limit which restricts the ultimate magnifying power of telescopes and other optical devices.
This is a fast-moving field and nobody knows how much further it will advance in the next three years. But the results will certainly be worth watching.
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