@PhdThesis{duepublico_mods_00032850,
  author = 	{Saleh, Gameel},
  title = 	{High Impedance Surface -- Electromagnetic Band Gap (HIS-EBG) Structures for Magnetic Resonance Imaging (MRI) Applications},
  year = 	{2013},
  month = 	{Dec},
  day = 	{23},
  keywords = 	{EBG Structures; Soft Surfaces; MRI},
  abstract = 	{High Impedance Surface -- Electromagnetic Band Gap (HIS-EBG) structures are one class of Metamaterials with unique and useful electromagnetic properties. This thesis proposes the first application of EBG structures for Magnetic Resonance Imaging (MRI) applications, with the aim of improving effectiveness of coils in creating RF magnetic flux density inside the patient or a phantom.
The anti-phase currents in the metallic ground planes placed underneath transmit RF coils for ultrahigh field MRI represent the main reason for the reduction in RF magnetic flux density above these coils (inside the load). In addition, they support the propagation of surface waves which radiate from edges and corners wasting power in the back hemisphere.</br>
The objective of this thesis is to investigate the potential of improving the efficiency of a well-established RF coil for 7 Tesla MRI by replacing the standard ground planes with specially designed EBG structures which exhibit novel electromagnetic properties: The reflection of such structures exhibits a frequency range over which an incident electromagnetic wave does not experience a phase reversal, and the image currents appear in-phase rather than out of phase as they do on the standard ground planes. Due to this, the EBG structure is termed an artificial magnetic conductor. Furthermore, it suppresses the propagation of surface waves..</br>
In this thesis, novel EBG structures are proposed and fabricated, and their electromagnetic properties are characterized analytically, numerically, and are validated by measurements. The RF coil backed by our proposed EBG ground planes exhibits improvement in the magnetic flux density inside phantoms compared to the case when it is backed by conventional ground planes of the same dimensions..</br>
A novel multilayer offset stacked polarization dependent EBG structure is designed to work as a soft surface with anisotropic surface impedance. The designed structure solves the problem of the limited space available in MRI magnet bores. The RF coil backed by the proposed soft surface exhibits stronger magnetic field inside the phantom, while the electric field and the specific energy absorption rate values are reduced.},
  url = 	{https://duepublico2.uni-due.de/receive/duepublico_mods_00032850},
  file = 	{:https://duepublico2.uni-due.de/servlets/MCRFileNodeServlet/duepublico_derivate_00034510/Gameel_Saleh_Diss.pdf:PDF},
  language = 	{en}
}