Analysis and Design of a Quasi-TEM Slotted Tube Resonator for UHF-MRI

Abstract

Using the finite element method (FEM) and method of moments (MoM) in two dimensions, the electromagnetic (EM) analysis and design of a quasi-TEM slotted tube resonator (STR) are presented. The modeling of this resonator consists in analyzing the even- and odd-mode characteristic impedances (Z0e, Z0o),effective dielectric constants (εeffe , εeffo), the primary inductive and capacitive matrices ([L], [C]) and simulates the frequency response of S11 at the RF port of the designed inhomogeneous MRI probe using transmission line method (TLM). As an application, we present the design results of a UHF-MRI probe loaded with a human head model of average relative dielectric constant of 64 and using the optimum configuration of the TEM STR. The probe with high Q operates at 340 MHz (proton imaging at 8 T) and has -130.6 dB minimum reflections. The UHF-MRI probe using quasi-TEM STR is easy to construct, inexpensive, and simple to operate. Furthermore, the coil presented here may be constructed to work at different resonances frequencies.