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Design and Simulation of Electromagnetic Wave Broadband Absorbers Using Metallic and Graphene-based Structures Based on Circuit Theory

Arik, Kamaloddin | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48014 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Khavasi, Amin; Rejaei, Behzad
  7. Abstract:
  8. In this dissertation, we design and simulate Electromagnetic (EM) wave absorbers using periodic array of ultra-thin metallic ribbons, metallic disks and graphene disks based on circuit theory. The equivalent circuit for EM structures significantly eliminates the requirement of systems with advanced hardwares. Firstly, we categorize the metallic absorbers in the literature in two types: narrowband absorbers and broadband absorbers. Surface plasmon polariton, magnetic resonance, interference theory and localized surface plasmon are employed to illustrate the mechanism behind the narrowband absorption. Therefore, they will be the basis for classifying the narrowband absorbers in this work. However, absorbers with a narrow absorption reflect a large amount of incident light within a broad wavelength range. Such a property of wavelength sensitivity severely limits the application of EM absorbers in the areas of solar energy harvesting, to overcome this limitation, two common methods will be proposed such as mixing resonances by horizontal integration and vertical integration. Secondly, an angle-independent and ultra-wideband absorber of light is proposed by using periodic array of ultra-thin metallic ribbons on top of a lossless quarter-wavelength dielectric spacer placed on a metallic reflector. The proposed device is of the normalized bandwidth of in mid-infrared regime. However, it is polarization-dependent. Fulfilling the polarization-insensitivity feature of the absorbing structure, we propose two two-dimensional structures which contain subwavelength graphene disks and metallic disks with normalized bandwidth of and in terahertz and mid-infrared regimes, respectively. In the three abovementioned absorbers, we propose a fully analytical circuit model for the structure, and then the absorber is duly designed based on impedance matching concept
  9. Keywords:
  10. Circuit Model ; Electromagnetic Wave ; Metamaterial Absorbers ; Graphene-based Absorbers ; Broadband Absorption ; Plasmonic Absorbers

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