Cloak of invisibility closer than you think Thursday, 21 July 2016

British engineers are claiming to have demonstrated for the first time a practical cloaking device that allows curved surfaces to appear flat to electromagnetic waves.

Professor Yang Hao from the School of Electronic Engineering and Computer Science at Queen Mary University of London (QMUL) said the research might not lead to the invisibility cloak made famous in the Harry Potter stories yet but the demonstration could result in a step-change in how antennas are tethered to their platform. It could allow for antennas in different shapes and sizes to be attached in awkward places and a wide variety of materials.

“The design is based upon transformation optics, a concept behind the idea of the invisibility cloak," said Yang Hao.

“Previous research has shown this technique working at one frequency. However, we can demonstrate that it works at a greater range of frequencies making it more useful for other engineering applications, such as nano-antennas and the aerospace industry.”

The team coated a curved surface, similar to the size of a tennis ball with a nanocomposite medium, which has seven distinct layers (called graded index nanocomposite) where the electric property of each layer varies depending on the position. The effect is to ‘cloak’ the object: such a structure can hide an object that would ordinarily have caused the wave to be scattered

The underlying design approach has much wider applications, ranging from microwave to optics for the control of any kind of electromagnetic surface waves.

Yang Hao's colleague Dr Luigi La Spada said the study and manipulation of surface waves is the key to develop technological and industrial solutions in the design of real-life platforms, for different application fields.

“We demonstrated a practical possibility to use nanocomposites to control surface wave propagation through advanced additive manufacturing," said La Spada.

"Perhaps most importantly, the approach used can be applied to other physical phenomena that are described by wave equations, such as acoustics. For this reason, we believe that this work has a great industrial impact.”

[The left image shows the cloak not in use and the waveform disrupted. The right image shows the cloak in action and a noticeable improvement in the reconstruction of wavefronts. Image: QMUL]

Developing an innovation industry in Australia will be one of the topics of discussion at the Australian Engineering Conference 2016 in Brisbane on November 23-25.