Toward Enhanced Transmit Performance of Rectangular Dielectric Resonator Antenna Arrays for 7-T MRI Using Loop/Dipole Coupling Scheme
Daniel Wenz1,2
1CIBM Center for Biomedical Imaging, Lausanne, Switzerland, 2Animal Imaging and Technology, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland
Loop-dipole coupling scheme, which can excite orthogonal
dielectric modes in a rectangular dielectric resonator antenna arrays, provides
significant transmit performance gains when compared to a dipole-only coupling
scheme.
Fig. 4. Transmit performance of the 8-channel
dipole-fed rectangular dielectric resonator (RDR) array compared with the
16-channel loop-dipole coupled RDR array (circularly polarized mode). The 16-channel array yielded significantly higher B1+
(+35%) and SAR (+9%) efficiency in the center of the spherical phantom.
Fig. 2. Phantom measurements: MR images obtained for a single-element
loop- and loop-dipole-coupled rectangular dielectric resonator antenna. Three
different profiles were selected and signal intensity as a function of distance
was shown below.