Fig. 12.

Circular patch probe and interdigitated capacitor probe array with quadrifilar strip helix and lateral end strips: coronal (left) and sagittal (right) (a) simulated $\mid {\mathrm{B}}_1^{+}\mid$ efficiency, (b) measured GRE images, and (c) measured $\mid {\mathrm{B}}_1^{+}\mid$ efficiency inside of cylindrical phantom. Phasing shown in Table V and magnitude excitations a quarter of the magnitude of the circular patch. Geometric distortions (barreling aspect) of $\mid {\mathrm{B}}_1^{+}\mid$ are due to uncorrected non-linearity of the gradient coils.