Dear all,
I used to do research in the field of wireless power transfer, where I usually tried to maximize the coupling between two magnetic resonators. Now I am doing work in RF-coil-design for MRI and inductive decoupling between adjacent coils in the array is essential.
I have been looking for some sources of explanation but I haven't been successful.
I might think that because of the coupling between adjacent coils, there might occur the frequency splitting effect. It will reduce the voltage at the resonance in each coil, which in turn reduces the SNR of the system.
Are there any more reasons why we need to use inductive decoupling?
Thanks
Dr. Chu, Decoupling the coils in the array eliminates the splitting effect. This is easily seen by on a S12 or S22 measurement on a spectrum analyzer where reducing the overlap of two circular resonant RF coils to 11% of the coil area will reach a minimum and the spectral splitting will collapse.
This is described in the original NMR array coil paper by Roemer et. al - Magnetic Resonance in Medicine 16, 192-225 (1990). Since that paper additional methods that use capacitive and low-impedence pre-amps have been used to reduce coupling. The inductive and capacitive methods allow a high current to be run in the conductor to produce a strong RF magnetic field. The low-impedence amplifier technique reduces coil current to a very low value to reduce the coupling field. The first two techniques are strongly configuration dependent. The latter not as sensitive to orientation.
There is an extensive literature in this field. Much larger than can be listed here. I' m attaching the Roemer paper for your use.
Good luck in your research.