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Impact of different meander sizes on the RF transmit performance and coupling of microstrip line elements at 7 T.

PURPOSE
In this work, the transmit performance and interelement coupling characteristics of radio frequency (RF) antenna microstrip line elements are examined in simulations and measurements.


METHODS
The initial point of the simulations is a microstrip line element loaded with a phantom. Meander structures are then introduced at the end of the element. The size of the meanders is increased in fixed steps and the magnetic field is optimized. In continuative simulations, the coupling between identical elements is evaluated for different element spacing and loading conditions. Verification of the simulation results is accomplished in measurements of the coupling between two identical elements for four different meander sizes. Image acquisition on a 7 T magnetic resonance imaging (MRI) system provides qualitative and quantitative comparisons to confirm the simulation results.


RESULTS
Simulations point out an optimum range of meander sizes concerning coupling in all chosen geometric setups. Coupling measurement results are in good agreement with the simulations. Qualitative and quantitative comparisons of the acquired MRI images substantiate the coupling results.


CONCLUSIONS
The coupling between coil elements in RF antenna arrays consisting of the investigated element types can be optimized under consideration of the central magnetic field strength or efficiency depending on the desired application.