Duke University researchers who previously demonstrated invisibility cloaking in the lab have employed 3D printing to build their latest “cloak” – a disk that can block microwaves.
The thickness of the donut-like disk roughly matches one wavelength, and its combination of air and dielectric (insulating, nonconducting) composite material deflects microwaves. An object placed in the center effectively “disappears” when microwaves are aimed at it. Because of the properties of transformation optics (physics of electromagnetic radiation that behaves similarly to relativistic warping of space-time), the shell of the disk eliminates any backward reflection that a viewer or detector would use to see the object, and also suppresses shadows and scattering.
The cloaking disk is made of plastic, but another transparent polymer or glass would work equally well, the researchers say. Simulations shows that the cloak could be made thinner and larger in area, and could potentially work for shorter wavelengths…
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