Thursday, 17 March 2016

'Meta-Skin' Truly Cloaks Objects From Radar


Meta-Skin – Manipulate Electromagnetic Waves

A team at Iowa State University led by electrical and computer engineering professor Jiming Song together with associate professor Liang Dong have developed a meta-material known as `meta-skin’. Co-authors are Iowa State graduate students Siming Yang, Peng Liu and Qiugu Wang and the former Iowa State undergraduate Mingda Yang.Meta-materials are manmade materials which tend to have the potentials greater than the sum of their single components.

The meta-skin takes its name from meta-materials that are composites having properties which are not found in nature and can manipulate electromagnetic waves. They came up with rows of split ring resonators that were embedded in layers of silicone sheets and the electric resonators were filled with galinstan, a metal alloy which is liquid at room temperature with less toxic than the other liquid metals like mercury.

These resonators are small rings having an outer radius of 2.5 millimetres with a thickness of half a millimetre and have a 1 millimetre gap. This is required to create a small curved segment of liquid wire.The rings tend to create electric inductors while the gap creates electric capacitors.

Meta-material – Low Toxicity- Used Commercially

Together they tend to create a resonator which can trap and suppress specific radar waves at a particular frequency, according to the university, on stretching and flexing the polymer meta-skin, the same can be tuned in reducing the reflection of an extensive range of radar frequencies.

The engineers have created their meta-material after embedding rows of minute split-ring resonators within silicone sheets and these resonators comprise of liquid metal alloy galinstan that is gallium, indium and tin. It is used commercially having low toxicity when compared to the other liquid metals.

The meta-material when tested by the team on wrapping it round a dielectric cylindrical rod at various angles, it was observed that it did well and reached a radar suppression of around 75% in the 8 to 10 gigahertz range.

As per the Physics Factbook, the band is utilised for civil marine radar, tracking radar, airborne weather avoidance radar system to detect mortar as well as artillery projectile and police speed meters. The team reported in the journal Scientific Reports that inspite of constant measurements, the meta-skin did not show any signs of exhaustion.

Meta-material – Next-Gen Stealth Aircraft

The engineers are of the belief that their stretchy meta-material would one day cover next-gen stealth aircraft. Dong mentioned in a university press release that the long term goal is to shrink the size of these devices and then they could do it with higher frequency electromagnetic waves like visible or infrared light – the visible light, the holy grail for cloaking materials.

The engineer mentioned in their paper that the present meta-skin technology would find several applications in electromagnetic frequency tuning, scattering suppression and shielding. Doug who has a background in fabricating micro and nanoscale devices has been working with liquids and polymers while Song has expertise in looking for new applications of electromagnetic waves. Working together, they expect to prove an idea that the electromagnetic waves, the shorter wavelengths of visible light could be curbed with flexible, tuneable liquid-metal technologies.

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