RF excitation in 7 tesla MRI systems using monofilar axial-mode helical antenna

We present a novel RF exciter for traveling-wave magnetic resonance imaging (MRI) systems based on a monofilar axial-mode helical antenna. In specific, we present a bore-extended, subject-loaded monofilar helical antenna for 7-T (ultra-high magnetic field) MRI systems. By means of rigorous full-wave electromagnetic modeling, we confirm clear advantages of the novel exciter over the existing TW excitation methods, and its excellent performance in terms of circular polarization and uniformity of the RF magnetic field in simple phantoms inside MRI bores at 7 T.