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The invisibility cloak may be just around the corner. Researchers at the University of Texas in Austin have developed a new type of "active" invisibility cloak that could operate over a broad range of frequencies.

The new invisibility cloak could work over a broad range of frequencies, including visible light and microwaves. The key difference between the new active invisibility cloak and passive cloaks is electricity. By using a "superconducting thin film" that is electrically powered could far surpass the limits of current "passive" designs.

The researchers describe their new active design in a paper published in Physical Review Letters.

"Our active cloak is a completely new concept and design, aimed at beating the limits of [current cloaks] and we show that it indeed does," said Prof Andrea Alu, from the University of Texas at Austin.

"If you want to make an object transparent at all angles and over broad bandwidths, this is a good solution.

"We are looking into realizing this technology at the moment, but we are still at the early stages."

The first working model of an invisibility cloak was demonstrated in 2006 and successfully concealed a small copper cylinder by bending microwaves around it.

These early cloaks are mostly made of metamaterials-manmade materials with properties not found in nature. They are capable of bending radiation in ways that wouldn't otherwise be possible. The problem is these metamaterials are tuned to a very specific frequency and, ironically, actually create more scattered light so that the object stands out more than if it were uncloaked.

 "Our active cloak is a completely new concept and design, aimed at beating the limits of [current cloaks] and we show that it indeed does," said Andrea Alu, an electrical engineer at the University of Texas.

"If you want to make an object transparent at all angles and over broad bandwidths, this is a good solution,"Alu added. "We are looking into realizing this technology at the moment, but we are still at the early stages."

For now, a cloak that allows complete invisibility is "impossible" with current passive designs, according to the study team.