Related Experiment Video
Updated: Aug 13, 2026

Fabrication and Characterization of Superconducting Resonators
Published on: May 21, 2016
Electromagnetic characterisation of MR RF coils using the transmission-line modelling method
P J Cassidy1, S Grieve, K Clarke
1British Heart Foundation Molecular Cardiology Group, Department of Biochemistry, University of Oxford, South Parks Road, OX1 3QU, Oxford, UK. cassidy@bioch.ox.ac.uk
Abstract:
The Transmission-Line Modelling (TLM) method is applied to the electromagnetic characterisation of RF coils and samples for magnetic resonance imaging MRI. Theoretical verification was performed using a simple surface coil. Experimental verification was performed using Alderman-Grant and birdcage coils constructed for use on a 7 T micro-imaging system. The modelling method enabled electromagnetic characteristics of frequency response, electromagnetic field generation, energy stored and power loss to be determined. From these parameters, coil resonant modes, B1 field profiles, voltages, currents, quality factor (Q), pi/2 pulse length, and the equivalent lumped-element circuit components of resistance, inductance and capacitance were calculated. Equations are presented that enable a comprehensive electromagnetic characterisation of the RF coil and sample to be achieved based on the results of the TLM simulations. The use of the TLM method is extended to include the design of safe arbitrary multi-nuclear pulse sequences such that the specific absorption rate (SAR) of tissue, and RF coil component safety limits are not exceeded.
Related Concept Videos
Generating Electromagnetic Radiations
Electromagnetic Fields
However, the observation of Gauss's...
Mesh Analysis for AC Circuits
The process of harmonizing these impedances begins with a clear understanding of the input and output signals. Once these signals are known, the...
Equivalent Circuits for Practical Transformers
In a practical transformer, each winding exhibits resistance and leakage reactance. The winding...
Transmission-Line Differential Equations
Line Section Model
A circuit representing a line section of length Δx helps in understanding the transmission line parameters. The voltage V(x) and current i(x) are measured from the...
Traveling Waves: Lossless Lines

