Loading...

Excitation of Magnetic Surface Waves for Anomalous Reflection and Transmission of Electromagnetic Waves

Abbasnezhad, Farhad | 2012

557 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43326 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Rejaei, Behzad
  7. Abstract:
  8. The phenomenon of extraordinary transmission of electromagnetic waves through arrays of small holesin metallic plates has attracted the attention of many researchers in the past decade.This behavior may be utilized to fabricate extremely narrowband microwave or optical filters and near-field sensing devices where the sub-millimeter hole can act like a probe. Despite almost ten years of continuous research, however, the uncertainty regarding the mechanisms underlying this phenomenon somewhat persists. Different theories concerning the origin of such behaviors, including surface waves, diffraction of electromagnetic waves, and waveguide phenomenon inside holes and slits have been proposed. But the final, decisive, picture where the relative predominance of each of these effects is clarified is still to be found. For better understanding of these effects, especiallythe role of surface waves and waveguide modes inside the slits, we will investigate extraordinary transmission in the presence of magnetic materials. The importance of magnetic materials (such as ferrites) compared with conventional dielectric lies in their rather complicated magnetic permeability. At microwave frequencies, strong dependence of this permeability on frequency and its tensor nature lead to the propagation of waves with wavelengths much shorter than their electromagnetic counterparts (e.g. in dielectrics) and with values which may potentially depend of the direction of propagation. Besides, the permeability of these materials is a function of the applied static magnetic field which offers the possibility of adjusting their behavior.To this end we study the extraordinary transmission from a one-dimensional array of slitsfilled with magnetic materials and analyze the effect of the resulting magnetic waveguide modes on the described phenomenon(Second Chapter). Moreover, in order to further investigate the role of surface waves, we study another structure composed of a layer of magnetic material covered by a metallic grating (Chapter 3). Since at microwave frequencies metals act like perfect conductors, surface Plasmon waves do not exist and the only surface wave existing are due to the presence of the magnetic layer. It is then found that the dependence of these surface waves on the direction of propagation leads to the occurrence of double peaks of extraordinary transmission close to each other whose distance may be manipulated by varying the properties of the magnetic film.
  9. Keywords:
  10. Magnetic Materials ; Surface Magnetic Waves ; Electromagnetic Extraordinary Transmission

 Digital Object List

 Bookmark