USPTO Issues World’s First Invisibility Cloak Patent

Microwave invisibility cloak.

Earlier today Fractal Antenna Systems, Inc. announced that they have recently been awarded the first patent on an invisibility cloak by the United States Patent and Trademark Office — U.S. Patent No. 8,253,639, titled “Wideband electromagnetic cloaking systems.”  Invisibility cloaks have long been a prop in science fiction stories, such as the Harry Potter invisibility cloak or the device used to cloak the Romulan bird of prey in Star Trek.  The concept of invisibility goes back even much further in the writings of H.G. Wells and others.  But the science fiction invisibility cloaks seem to suggest that objects could be rendered invisible by diverting waves in a ‘see thru’ effect.  That is at least the path that these cloaks inspired researchers to take, seemingly to great affect.

The ‘639 patent disclosure relates to techniques for cloaking objects at certain wavelengths / frequencies or over certain wavelength / frequency ranges (bands). Such techniques can provide an effective electromagnetic lens and/or lensing effect for certain wavelengths / frequencies or over certain wavelength / frequency ranges (bands).  Representative frequencies of operation can include, but are not limited to, those over a range of 500 MHz to 1.3 GHz. Operation at other frequencies, including for example those of visible light, infrared and ultraviolet are also contemplated by the disclosure and could be achieved by appropriate scaling of dimensions and selection of shape of the resonator elements.

According to the inventor, Nathan Cohen, who is an astrophysicist and expert in optics, a viable infrared invisibility cloak is months away and a visible light cloak perhaps two years away. Notwithstanding, the patenting of the world’s first invisibility cloak is a milestone in innovation.

Cohen notes that some in the public may believe invisibility cloaks had been realized and invented as far back as 2006, by others. “In truth, the patent office has rejected their claims for an invisibility cloak,” said Cohen. “Fractal’s award of Patent 8,253,639 is the first invisibility cloak patent award.”

The patent claims awarded in the ‘639 patent do seem somewhat broad, which could make this patent an important, pioneering patent.  Claim 1 covers the following:

1. An electrical resonator system, comprising: a plurality of concentric electrical resonator shells, each shell including a substrate having first and second surfaces and a close-packed arrangement of electrically conductive material formed on the first surface, wherein the closed-packed arrangement comprises a plurality of self-similar electrical resonator shapes and is configured to operate at a desired passband of electromagnetic radiation; wherein the close-packed arrangements of at least two of the electrical resonator shells are different in size and/or shape; and wherein a resonator in the close-packed arrangement comprises a second order or higher fractal.

Fractal Antenna Systems has geared up development and production for invisibility cloak applications. First uses will be to improve coverage in ‘blind spots’ for microwave telecommunications and to remove antenna shadows. This use is explained in a 6 minute video produced by the company and uploaded to YouTube, which you can see below:

The company is also giving public demonstrations at colloquia and conferences. “It’s real. Come and see it. With the issued patent there’s nothing to hide, except maybe Harry,” said Cohen.

For those interested in more discussion of cloaking from a scientific, but approachable level, take a look at How Invisibility Cloaks Work on



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2 comments so far.

  • [Avatar for Stan E. Delo]
    Stan E. Delo
    September 8, 2012 09:44 pm


    Thanks for letting us know about this very interesting turn of events, and for the patent number. I believe you are correct about earlier posits in this direction, as I seem to recall an earlier hint at cloaks in the visible light band from about 6 years ago, so 2006 seems to make sense. I can’t recall who suggested it, but I do know it was from an optics and photonics expert, so perhaps the same person?

    One theory is to bend light around objects using gravity, which gives rise to a circle of light feature being evident were one to go beyond the event horizon of a black hole for instance, where the photons are in orbit, instead of being either eaten or allowed to escape. Of course no human could survive such an event to be able to report it, so it is all just theory and conjecture at the present time.

    Thanks for the further reading link, which sounds worth looking into.


  • [Avatar for Steve M]
    Steve M
    September 8, 2012 05:59 pm

    Then again, many politicians have been “cloaking” for some centuries now.

    Guess that doesn’t qualify as prior art, though. 🙂