Characterization of the RF field for metamaterial-based structures constructed of conducting strips and a dielectric at 7T MRI

Metamaterial-based structures constructed of conducting strips and a dielectric have already been used to locally increase the RF transmit field. In this study we characterize the RF field of such structures at 7T MRI. Configurations included either long strips (representing electric dipoles), or a matrix of short strips (representing magnetic dipoles). The RF field dependence on strip density and distribution was analyzed, providing insights useful for efficiency and coverage optimization. The configuration based on a matrix of short strips provides higher RF transmit efficiency, while the use of a non-uniform concave distribution of strips is useful to lower SAR.