A dynamic vector model of microstrip RF resonators for high-field MR imaging.
This paper describes a dynamic vector model for modelling the electromagnetic characteristics of microstrip radio-frequency (RF) resonators for high field magnetic resonance imaging (MRI). A biological tissue-equivalent load having a circular cross section is assumed in the analysis. The dynamic model uses the well-known Green's function for cylindrically stratified media to characterize all six components of the electromagnetic field excited by the microstrip lines. The accuracy of the method as a function of its parameters is assessed and the results compared with those obtained from the quasi-static method often used at low frequencies. The limits of the quasi-static assumption are investigated by comparing values for the modal propagation constant and the terminating capacitances required to tune the cavity resonance over a frequency range of 100 MHz-1 GHz. The dynamic method is further used to analyse the modal content of a microstrip head resonator. Finally, a variational approach is used to assess the impact of the intermodal coupling for the case of small perturbations in the shape and the position of the cylindrical phantom.
George Green Institute for Electromagnetics Research, School of Electrical and Electronic Engineering, University of Nottingham, University Park, Nottingham, NG7 2RD, UK. Ana.Vukovic@nottingham.ac.uk
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A
Vukovic
P
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Sewell
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McKirdy
D
D
Thomas
T M
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Benson
C
C
Christopoulos
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Glover
D000465:Algorithms; D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007089:Image Enhancement / Q000295:instrumentation* / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods; D008280:Magnetics / Q000295:instrumentation*; D008954:Models, Biological; D011846:Radio Waves; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014159:Transducers