General design approach and practical realization of decoupling matrices for parallel transmission coils
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A general design.pdf
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Author(s)
Guérin, Bastien
Keil, Boris
Vester, Markus
Wald, Lawrence L.
Mahmood, Zohaib
McDaniel, Patrick C.
Adalsteinsson, Elfar
Daniel, Luca
Date Issued
June 2016
Journal
Magnetic Resonance in Medicine
Publisher
Wiley Blackwell
Citation
Mahmood, Zohaib; McDaniel, Patrick; Guérin, Bastien et al. “General Design Approach and Practical Realization of Decoupling Matrices for Parallel Transmission Coils.” Magnetic Resonance in Medicine 76, 1 (July 2015): 329–339 © 2015 Wiley Periodicals, Inc
Version
Author's final manuscript
Abstract
Purpose
In a coupled parallel transmit (pTx) array, the power delivered to a channel is partially distributed to other channels because of coupling. This power is dissipated in circulators resulting in a significant reduction in power efficiency. In this study, a technique for designing robust decoupling matrices interfaced between the RF amplifiers and the coils is proposed. The decoupling matrices ensure that most forward power is delivered to the load without loss of encoding capabilities of the pTx array.
Theory and Methods
The decoupling condition requires that the impedance matrix seen by the power amplifiers is a diagonal matrix whose entries match the characteristic impedance of the power amplifiers. In this work, the impedance matrix of the coupled coils is diagonalized by a successive multiplication by its eigenvectors. A general design procedure and software are developed to generate automatically the hardware that implements diagonalization using passive components.
Results
The general design method is demonstrated by decoupling two example parallel transmit arrays. Our decoupling matrices achieve better than −20 db decoupling in both cases.
Conclusion
A robust framework for designing decoupling matrices for pTx arrays is presented and validated. The proposed decoupling strategy theoretically scales to any arbitrary number of channels.
MIT Department
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
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Creative Commons Attribution-Noncommercial-Share Alike
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DOI of Published Version
https://doi.org/10.1002/mrm.25855
