Numerically Shown Multiple Frequency Active Cloaking of Any Shape Object by Devices that Generate EM

These images are from animated computer simulations of a new method — developed by University of Utah mathematicians — for cloaking objects from waves of all sorts. While the new method is unlikely to lead to invisibility cloaking like that in ‘Star Trek’ or ‘Harry Potter’ movies, it may eventually help shield submarines from sonar, planes from radar, buildings from earthquake waves, and oil rigs and coastal structures from tsunamis. The top three images show a wave front passing the kite-shaped object in the middle and hitting the object as it does. In the bottom three images, the kite-shaped object if surrounded by three cloaking devices and the waves they emit. So when the wave front passes, it moves by the object without touching it. Photo Credit: Fernando Guevara Vasquez

University of Utah mathematicians developed a new cloaking method which someday might shield submarines from sonar, planes from radar, buildings from earthquakes, and oil rigs and coastal structures from tsunamis.

We have shown that it is numerically possible to cloak objects of any shape that lie outside the cloaking devices, not just from single-frequency waves, but from actual pulses generated by a multi-frequency source,” says Graeme Milton, senior author of the research and a distinguished professor of mathematics at the University of Utah.

It’s called active cloaking, which means it uses devices that actively generate electromagnetic fields rather than being composed of ‘metamaterials’ [exotic metallic substances] that passively shield objects from passing electromagnetic waves.”

Radar microwaves have wavelengths of about four inches, so Milton says the study shows it is possible to use the method to cloak from radar something 10 times wider, or 40 inches. That raises hope for cloaking larger objects. So far, the largest object cloaked from microwaves in actual experiments was an inch-wide copper cylinder.

Most previous research used interior cloaking, where the cloaking device envelops the cloaked object. Milton says the new method “is the first active, exterior cloaking” technique: cloaking devices emit signals and sit outside the cloaked object.

The new studies are numerical and theoretical, and show how the cloaking method can work. “The research simulates on a computer what you should see in an experiment,” Milton says. “We just do the math and hope other people do the experiments.”

The Physical Review Letters study demonstrates the new cloaking method at a single frequency of electromagnetic waves, while the Optics Express paper demonstrates how it can work broadband, or at a wide range of frequencies.

In Optics Express, the mathematicians demonstrate that three cloaking devices together create a “quiet zone” so that “objects placed within this region are virtually invisible” to incoming waves.