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  • METAMATERIALSMetamaterials 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.Whats a double negative (DNG) medium and how does it work?Backward waves and negative refraction Applications

  • Double Negative Media (DNG)DPSMNGENGDNGSNGpropagationevanescencepropagationIsotropic and homogeneous

  • Backward PropagationEHRight-handed MediumkEkHLeft-handed MediumSSDPS mediumDNG medium

  • Negative RefractionkiktkrqiqtqrairkiktkrqiqtqrairDPSDNGRegular refractionNegative refraction

  • Negative Refraction Index (NRI)Snells LawV. G. Veselago

  • Pendry Perfect LensAdt-dtPendryThe lens focuses all the planes waves radiated by a dipole source (even the evanescent waves), with no phase or amplitude distortion

  • Material DispersionDNG metamaterials:can be achieved by frequency resonance of a mixture of metallic and/or dielectric particles in a host medium.Electric plasma frequencyElectric resonance frequencyMagnetic plasma frequencyMagnetic resonance frequency.Negative permittivity (effect of wires)Negative permeability (effect of rings)

  • 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.Metamaterial, which response should be homogeneous on the scale of the wavelength.SRR provides a resonant structure which is much smaller than the resonance wavelength.

  • The Split Ring Resonator (SRR)

  • Waveguide ExperimentsMetallic rectangular waveguide: TE01 modeWaveguide miniaturizationSWRGunnb

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

  • Double Negative MediaD. R. Smith and S. Schultz, UCSD

  • DNG WaveguidesDNGDPSDPSP1P2P2DNG slab waveguideDNGDPSDNG/DPS directional couplerP1P2Back propagation

  • ApplicationsDNG Cloaking devices Metamaterial antennas: increased performance and miniaturization