Control of the RF magnetic field pattern by tunable metasurface in 1.5 T MRI

Abstract

Abstract A metasurface with a unit cell in the form of a half-wave dipole can be used as a base for the creation of wireless coils for magnetic resonance imaging (MRI). In a real structure based on a metasurface concept, the number of elements is always limited. Therefore, some elements at the edges become weaker coupled and radiofrequency (RF) magnetic field pattern becomes distorted. In this paper, we investigate metasurface-based structure with added non-uniform electrical capacitance at the ends of the resonant unit cells. We show that such a structure can be easily adjusted to work within the frequency range of the clinical 1.5 T MRI machine. Also, we demonstrate that by adding of non-uniform edge capacitances at the resonant elements, it is possible to control the RF magnetic field pattern above the structure.