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METAMATERIALS

METAMATERIALS. Metamaterials are artificial engineered composite structures that can be designed to exhibit specific electromagnetic properties not observed in the constituent materials and not commonly found in nature. What’s a double negative (DNG) medium and how does it work?

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METAMATERIALS

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  1. METAMATERIALS Metamaterials are artificial engineered composite structures that can be designed to exhibit specific electromagnetic properties not observed in the constituent materials and not commonly found in nature. • What’s a double negative (DNG) medium and how does it work? • Backward waves and negative refraction • Applications

  2. Double Negative Media (DNG) Isotropic and homogeneous ENG MNG DNG DPS propagation propagation SNG evanescence

  3. Backward Propagation DNG medium DPS medium E E k S k S H H Right-handed Medium Left-handed Medium

  4. Negative Refraction ki ki kr kr qr qr qi qi air air DNG DPS qt qt kt kt Regular refraction Negative refraction

  5. Negative Refraction Index (NRI) Snell’s Law V. G. Veselago

  6. B Pendry Perfect Lens The lens focuses all the “planes waves” radiated by a dipole source (even the evanescent waves), with no phase or amplitude distortion A Pendry d t t-d

  7. Material Dispersion DNG metamaterials: can be achieved by frequency resonance of a mixture of metallic and/or dielectric particles in a host medium. Electric plasma frequency Electric resonance frequency “Magnetic plasma frequency” Magnetic resonance frequency. Negative permittivity (effect of wires) Negative permeability (effect of rings)

  8. The Split Ring Resonator (SRR) - + - + External magnetic field penetrates through the rings and currents are induced. Gap prevents currents from flowing around the ring, which considerably increases the resonance frequency of the structure. SRR provides a resonant structure which is much smaller than the resonance wavelength. Metamaterial, which response should be homogeneous on the scale of the wavelength.

  9. The Split Ring Resonator (SRR)

  10. Waveguide Experiments Metallic rectangular waveguide: TE01 mode b Gunn SWR Waveguide miniaturization

  11. Array of Metallic Wires For long wavelengths an array of metallic wires interacts with electromagnetic waves as a plasma, and thus exhibits a negative permittivity below the plasma frequency:

  12. Double Negative Media D. R. Smith and S. Schultz, UCSD

  13. DNG Waveguides DPS P2 DNG P1 DNG P1 DPS P2 DPS P2 DNG slab waveguide DNG/DPS directional coupler Back propagation

  14. Applications • Cloaking devices • Metamaterial antennas: increased performance and miniaturization DNG

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