|
Metamaterials
Updated March
29, 2010
Click
here to go to our page on permittivity
click
here to go to our page on permeability
We now have a technical description
of metamaterials, from a university student in India. Check
it out!
Metamaterials are a class of
artificial material structures comprised of patterned metal and
dielectric layers. Metal features are small compared to wavelength,
and the features are periodic.
By carefully engineering the
structure, a negative index of refraction can occur at specific
frequencies. Looking at this another way, the Poynting
vector no longer obeys the right-hand rule; this is what give
metamaterials the nickname "left-handed materials". Note
that negative refraction is not the equivalent of perpetual
motion, it just means that EM energy bends in the opposite direction
you'd think it would when it encounters left-handedness.
The index is a function of the
permittivity and permeability
of a material:

it is also equal to the the speed
of light in vacuum divided by the phase
velocity in the material:

What can we do with this new
class of materials at microwave frequencies? The number one suggestion
for microwave application is as stealth technology, or in words
James T. Kirk would understand, as a cloaking device. But the utility
of such a device is expected to be limited, it might only spoof
your enemies if they used a specific frequency and illuminated your
hardware at a specific angle. There might also be some interesting
ways to use metamaterials in antennas. Optical metamaterials might
have a bright future in Las Vegas, as part of a magic act. Now you
see it, now you don't!
Even though we want to
give metamaterials the benefit of the doubt, it is mentioned on
on our career-killer page.
|