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Surface Integral Equations Technique for Ferrite Resonator Antennas

Norouzzadeh, Elham | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45849 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Rejaei, Behzad
  7. Abstract:
  8. So far, investigations have shown that open dielectricresonator antennas(DRAs) offer several advantages at microwaveand millimeter wave frequencies and make them appropriate in low directional-gain applications . These advantages include small size, large impedance bandwidth, high radiation efficiency, ease of manufacturing and simple feed-coupling mechanisms (such as probe coupling, aperture coupling or proximity coupling to micro-strip lines). Most microwave ferrites have dielectric constants in the desirable range and they can be used in place of dielectric materials. Such ferrite resonator antennas (FRAs) offer a potential advantage inthat their permeability tensor can be controlled by applying an external magnetic field. Up to now and by the application of a magnetic field, properties such as resonant frequency agility and polarization agilityhave been demonstrated experimentally.Several studies is performed to obtain an analytical formula for this type of antenna.But due to the complexity of the permeability tensor of ferrite, provided models of ferrite resonator antenna was not perfect. In the existing models, tensor natureof the ferrite was disregarded or analysis were carried out for propagation of just a single waveguide mode. To our knowledge, analytical formulation of the FRAhas been limited to introducing effective scalar permeability coefficients (instead of its original tensor)and then modeling it as a simple dielectric cavity. Inthis thesis the cylindrical shaped FRA which is magnetically saturated parallel to its axis has been studied. In the first step effortshave been made to calculate dyadic green’s function for Infinite space surrounded by ferritewhich is magnetically saturated in z direction. In the next step surface integral equations on surface of FRA which has been placed on the infinite PEC ground and fed by a coaxial cable, was calculated and with use of this results complete description of performance indicators of antenna for example, radiation pattern, efficiency and radiation impedance is provided
  9. Keywords:
  10. Ferrite Resonator Antenna ; Microwave Ferrites ; Surface Integral Equations

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