Metafilms to Shrink Radio Devices

Metamaterials promise us optical and acoustic invisibility, even if, for now, such phenomenons are restricted to certain wavelengths and 2-dimensional use. Scientists now believe that, by using the electromagnetic properties of metamaterials, smaller resonating circuits can be produced (such as those generating microwave radiation), thus shrinking electronic devices like radio equipment or cellular telephones.

Metamaterials are artificial composites which are fabricated by creating intricate metal structures, giving them the unique capability to experience weird electromagnetic properties, such as stopping light on its way. New simulations conducted by National Institute of Standards and Technology researchers reveal that metamaterials created from metallic patches with special dielectric properties in a two dimensional configuration can cause electromagnetic energy reflected on its surface to behave in a unique way.

The effects of metafilms, as they are called, placed inside a common resonator have been easily deduced by NIST researchers. Resonators are cavities where microwave radiation is continuously bounced back and forth, and can be tuned to radiate and detect only specific frequencies of the electromagnetic spectrum.

For example, a resonator cavity has to be about half of the wavelength of the frequency which must be radiated or detected, thus for a frequency of 1 gigahertz the resonator cavity needs to be approximately 15 centimeters in length. You can't have cellular telephone with a resonator chamber 15 centimeters long, however researchers revealed that the size can be drastically decreased by simply placing a bulk metamaterial inside it.

This was also the goal of the team from NIST, but instead of using bulk material, they argued they can achieve the same performance with the help of a metafilm. The advantages opposed to bulk metamaterials are obvious: first of all, the space required for such a resonator is much smaller; secondly, by using metafilms, energy loss is minimized.

With their unique electromagnetic properties, metafilms, and metamaterials in general, are able to shift the phase of the electromagnetic energy bounced inside the resonator cavity, thus making it appear much longer than it actually is. It is like space suddenly expands inside the film as radiation passes through it.

Lead author of the study Chris Holloway says that this effect is due to the scattering properties of the intricate structure, which is able to trap electromagnetic radiation locally. The immediate response is a change in microwave phase in order to establish resonance conditions.

On the other hand, although ametafilm can create smaller resonators, the factor quality is much lower than that of traditional resonators, meaning that a balance between frequency and the factor quality must be reached in order to obtain a working device.



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