Defense Intelligence Reference Document Metamaterials For Aerospace Applications

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The electric response of such (or similar) metamaterial is given by
ai
&(Ill)= f - l l' .
or-m; +10Jy (2)
where ma is the resonant frequency and r is the loss coefficient.
Negative index metamaterials are by no means the only potentially useful metamedia.
Several new concepts such as Indefinite Permittivity Metamaterials (IPM) (References
3, 4) and Epsilon-Near-Zero (ENZ) metamaterials (Reference 5) have recently emerged
and found some exciting applications that will be reviewed below. IPMs can be used as
ultra-compact spatial filters (both high-pass and low-pass) whereas ENR metamaterials
can be·used for making sub-wavelength waveguides capable of coupling close to 100
percent of the incident radiation (Reference 8), as well as directing it around tight
bends with negligible bending losses. Yet another class of planar metamaterials,
complementary metamaterials (CMMs), has recently emerged (Reference 7). Instead of
using metallic structures deposited on a substrate (left panel of Figure 3), CMMs consist
of slits in the continuous metal screen (right panel of Figure 3). The shape of the slits
coincides with that of the materials themselves. Such complementary metamaterials
have been recently used for making epsilon-near zero waveguides (Reference 8).
CE4
CE5
CE3 CE6
Figure 3. Geometry of Orlglnal Planar Metamaterlal Unit Cells (OE1-0E6) and Their Complements
(CE1-CE6). The polarization of normally Incident electromagnetlc radiation ls configured as shown ln OEl
and CEl for the original and complementary metamaterials, respectively, (Reference 9)
3
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