Researchers unveiled cloaking technology that the US military has been waiting for

via businessinsider.com

via businessinsider.com

Breakthrough research from the University of California-San Diego could take the US military one step closer towards having cloaked aircraft and drones.

Researchers Li Yi Hsu, Thomas Lepetit, and Boubacar Kante have succeeded in creating an ultra thin “dielectric metasurface cloak,” which is composed of a multitude of ceramic cylinders embedded into a layer of Teflon.

Like an invisibility cloak, this coating could mask objects from visible light and radio wavelengths, the Army Times notes, and the military is paying attention.

“I am very excited about this work,” Kante told the Army Times.

The cloak functions by either absorbing or directing electromagnetic waves away from an object. This, in turn, effectively masks the object making it ‘invisible.’ While experiments in 2006 first showcased a limited degree of invisibility cloaking, the new breakthrough has two main advantages over older methods.

First, Kante told the Army Times, the new material his team discovered uses ceramics rather than metal particles making the material easier and cheaper to manufacture. Second, the method of using ceramics and Teflon allows the cloak to be effective with coating layers as thin as millimeters.

“Previous cloaking studies needed many layers of materials to hide an object, the cloak ended up being much thicker than the size of the object being covered,” Hsu said in a statement. “In this study, we show that we can use a thin single-layer sheet for cloaking.”

These advantages make a world of difference in real world applications, which is why the military has taken a keen interest in the new cloak. Whereas older cloaking technology would have required 30cm of Teflon coating to mask a Predator drone from a surveillance system, the new cloaking technology could hide the same drone from the same radar with only 3mm of coating, the Washington Post reports.

This suddenly takes the idea of cloaking away from the realm of sci-fi and moves it firmly towards real world applications. Kayla Matola, a research analyst with the Homeland Defense and Security Information Analysis Center, told the Army Times that the new cloaking technology is “basically what the military’s looking for.”

“If anything this could provide the military with air superiority,” Matola told the Army Times.

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New theory leads to radiationless revolution

IMAGE: DR. MIROSHNICHENKO WITH HIS VISUALIZATION OF ANAPOLES AS DARK MATTER CREDIT: STUART HAY, ANU

IMAGE: DR. MIROSHNICHENKO WITH HIS VISUALIZATION OF ANAPOLES AS DARK MATTER
CREDIT: STUART HAY, ANU

Physicists have found a radical new way confine electromagnetic energy without it leaking away, akin to throwing a pebble into a pond with no splash

Physicists have found a radical new way confine electromagnetic energy without it leaking away, akin to throwing a pebble into a pond with no splash.

The theory could have broad ranging applications from explaining dark matter to combating energy losses in future technologies.

However, it appears to contradict a fundamental tenet of electrodynamics, that accelerated charges create electromagnetic radiation, said lead researcher Dr Andrey Miroshnichenko from The Australian National University (ANU).

“This problem has puzzled many people. It took us a year to get this concept clear in our heads,” said Dr Miroshnichenko, from the ANU Research School of Physics and Engineering.

The fundamental new theory could be used in quantum computers, lead to new laser technology and may even hold the key to understanding how matter itself hangs together.

“Ever since the beginning of quantum mechanics people have been looking for a configuration which could explain the stability of atoms and why orbiting electrons do not radiate,” Dr Miroshnichenko said.

The absence of radiation is the result of the current being divided between two different components, a conventional electric dipole and a toroidal dipole (associated with poloidal current configuration), which produce identical fields at a distance.

If these two configurations are out of phase then the radiation will be cancelled out, even though the electromagnetic fields are non-zero in the area close to the currents.

Dr Miroshnichenko, in collaboration with colleagues from Germany and Singapore, successfully tested his new theory with a single silicon nanodiscs between 160 and 310 nanometres in diameter and 50 nanometres high, which he was able to make effectively invisible by cancelling the disc’s scattering of visible light.

This type of excitation is known as an anapole (from the Greek, ‘without poles’).

Read more: New theory leads to radiationless revolution

 

 

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Tailored flexible illusion coatings hide objects from detection

Antenna covered with copper patterned dielectric substrate creates a flexible metasurface that acts as an illusion coating, cloaking the antenna or making it appear to be something entirely different. Image: Zhihao Jiang/Penn State

Antenna covered with copper patterned dielectric substrate creates a flexible metasurface that acts as an illusion coating, cloaking the antenna or making it appear to be something entirely different.
Image: Zhihao Jiang/Penn State

Developing the cloak of invisibility would be wonderful, but sometimes simply making an object appear to be something else will do the trick, according to Penn State electrical engineers.

“Previous attempts at cloaking using a single metasurface layer were restricted to very small-sized objects,” said Zhi Hao Jiang, postdoctoral fellow in electrical engineering, Penn State. “Also, the act of cloaking would prevent an enclosed antenna or sensor from communicating with the outside world.”

Jiang and Douglas H. Werner, John L. and Genevieve H. McCain Chair Professor of Electrical Engineering, developed a metamaterial coating with a negligible thickness that allows coated objects to function normally while appearing as something other than what they really are, or even completely disappearing. They report their research in Advanced Functional Materials.

The researchers employ what they call “illusion coatings,” coatings made up of a thin flexible substrate with copper patterns designed to create the desired result. They can take a practical size metal antenna or sensor, coat it with the patterned film and when the device is probed by a radio frequency source, the scattering signature of the enclosed object will appear to be that of a prescribed dielectric material like silicon or Teflon. Conversely, with the proper pattern, they can coat a dielectric and it will scatter electromagnetic waves the same as if it were a metal object.

“The demonstrated illusion/cloaking coating is a lightweight two-dimensional metasurface, not a bulky three-dimensional metamaterial,” said Werner.

The researchers take the object they want cloaked and surround it with a spacer, either air or foam. They then apply the ultrathin layer of dielectric with copper patterning designed for the wavelengths they wish to cloak. In this way, antennae and sensors could be made invisible or deceptive to remote inspection.

Another application of this material would be to protect objects from other emitting objects nearby while still allowing electromagnetic communication between them. This was not possible with the conventional transformation optics-based cloaking method because the cloaking mechanism electromagnetically blocked the cloaked object from the outside, but this new coating allows the object surrounded to continue working while being protected. In an array of antennae, for example, interference from the nearby antennas can be suppressed.

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A smart fluorescent antenna for Wi-Fi applications

A charged argon gas in the fluorescent lamp emits Wi-Fi signals. Copyright : Faculty of Electrical Engineering, Universiti Teknologi MARA

A charged argon gas in the fluorescent lamp emits Wi-Fi signals.
Copyright : Faculty of Electrical Engineering, Universiti Teknologi MARA

A new invention uses ionized gas in fluorescent light tubes to transmit Internet wireless frequency signals throughout a building with the aid of already existing electrical wiring.

Due to continuously evolving applications, the electronic communications industry requires high performance and speed efficient systems. However, the physical limitations of microwave devices limits further improvements in current technology. This predicament has led to growing interest in the use of plasma as a conductive element in microwave devices due to their unique and innovative properties, which corresponds with traditional metallic antennas.

Matter exists in four different states: solid, liquid, gas and plasma. Plasma is a type of gas in which the atoms are ionized – they have both free negatively charged electrons and positively charged ions. These charged particles can be controlled by electromagnetic fields, allowing plasmas to be used as a controllable reactive gas.

This invention employs an ionized gas enclosed in a tube as the conducting element of an antenna. When the gas is electrically charged or ionized to plasma, it becomes conductive and allows radio frequency signals to be transmitted or received. When the gas is not ionized, the antenna element ceases to exit.

The invention features a smart fluorescent antenna with a 3G/3.75G/4G router for Wi-Fi applications. The antenna operates at the 2.4 GHz frequency band, which is suitable for Wi-Fi applications. A commercially available fluorescent tube, measuring 0.61 metres in length by 0.25 metres in diameter, is used as the plasma antenna. The gas inside the tube is a mixture of argon and mercury vapour, in the ratio 9:1. The tube is energized by a 240 V current, provided by a standard AC power supply. A glowing tube indicates that the gas inside the tube has been ionized to plasma and forms a plasma column. In this state, the plasma column becomes highly conductive and can be used as an antenna.

A coupling sleeve is positioned at the lower end of the tube, which is used to connect the plasma tube to the router. The function of the coupling sleeves is to store the electrical charge. When the gas inside the tube is sufficiently ionized into a plasma state, it becomes conductive and allows radio frequency signals to be transmitted or received.

Measurements indicate that the plasma antenna yields a return loss over 10 dB in the 2.23 GHz to 2.58 GHz frequency band. The antenna’s ability to operate as either a transmitter or receiver in this particular frequency band was verified through a series of wireless transmission experiments.

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Stanford Engineer’s Electrifying Breakthrough

28-06-2014 9-27-50 PM

Engineers at Stanford University are hoping that an emerging technology could someday be used to treat diseases in an entirely different way. 

The engineers say the breakthrough started with the challenge of miniaturizing a small pacemaker. And for Stanford professor Ada Poon, Ph.D., it’s just part of a bigger plan to fight disease, by changing the way we think about electricity.

“We came up with a new way to wirelessly power tiny medical devices that could be placed very deep inside the body,” Poon said.

To charge those tiny devices without batteries, the Stanford team began experimenting with a new way to project electricity safely into the human body. The system they came up with employs electromagnetic waves similar to those used to power an electric toothbrush. 

But researcher John Ho says once the waves enter the body, they begin a kind of natural acceleration. 

“Taking advantage of the simple fact that properties of waves change as they move from one type of material to another,” Ho said. “These near field waves are converted into propagating waves. And they travel much farther than they would otherwise.”

Several inches into the body, in fact — deep enough to reach the miniaturized pacemaker and power it.

“We demonstrated we can blend the safety of the near field with the propagation of the far field,” Poon said.

Powering a new generation of miniaturized devices would be a medical breakthrough in itself. But the Stanford team believes their system has the potential to do much more, like treating disease with electricity.

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