New Invisibility Cloak Augments Metamaterial Base with Electronics to Improve Performance
Alù’s proposed design consists of a conventional metamaterial base, but with CMOS negative impedance converters (NICs) placed at the corner of each metamaterial square.
A NIC is an interesting electronic component that adds negative resistance to a circuit, injecting energy rather than consuming it. NICs are not widely used as we’re not entirely sure how to use them.
Alù seems to propose that by interspersing NICs (which must be powered) with the metamaterial, multiple frequencies can be cloaked. In the image above, you can see a standard metamaterial cloak (blue), vs Alù’s metamaterial-and-NIC cloak (green).
Alù’s proposed cloak is invisible over a large range of frequencies, while a standard passive cloak is only invisible for a small range, and more visible than non-cloaked devices in other ranges.
(via New invisibility cloak combines metamaterials and fancy electronics to be thinner, lighter, more invisible | ExtremeTech)