Fast and Efficient Birdcage Coil Design Process for High Field MRI System by Combining Equivalent Circuit Model and 3D Electromagnetic Simulation

A Simple Analytical Solution for the Designing of the Birdcage RF Coil Used in NMR Imaging Applications

“…However, the port impedance as viewed from the external circuit would be different at both positions which results in different expressions for the general analytical solution. By considering the port connected across the end-ring segment Zer/2, the general analytical solution can be developed by calculating the equivalent impedance of the circuit model shown in Figure 6 The final expression of the general analytical solution for the case when the port is created in the end-ring segment is given by the equation (21). The equivalent circuit impedances Z ER and Z L can be determined by using the elements of the equivalent transmission matrix T e with the help of following Equations ( 15) and ( 16) respectively.…”

“…The proposed analytical solution given in Section 1 does also provide the information about the resonance frequency modes for all three configurations (low pass, high pass and band pass) of the birdcage RF coil by plotting its input impedance Z ER_p against frequency. We assumed the case where the receiver port is connected across the half end-ring segment and then determined the resonance frequencies spectrum of all three coil configurations using Equation (21). The effective inductance values of the leg and end-ring segments along with their corresponding effective capacitance values (with respect to the coil configuration) were used to compute the impedances Z l and Z er .…”

“…In this paper, we have introduced a new concept of the dominant resonance path for the birdcage RF coil which is a simple and intuitive designing technique. The method works by identifying the closed current loop in the birdcage RF coil who is responsible of causing the dominant resonance frequency which is used for NMR imaging applications [21]. The proposed strategy provides rather convenient way to determine the lumped capacitances for the leg and end-ring segments of the birdcage RF coil for its proper operation at desired dominant resonance frequency.…”

“…The proposed strategy provides rather convenient way to determine the lumped capacitances for the leg and end-ring segments of the birdcage RF coil for its proper operation at desired dominant resonance frequency. We have also devised a simple analytical solution for the birdcage RF coil by establishing it equivalent circuit model which is based upon the transmission matrix theory [21,22]. The proposed analytical solution provides the mathematical expression for the input impedance Z in of the birdcage RF coil as seen from the port in terms of the impedances of its leg and end-ring segments.…”

Recent Progress in Birdcage RF Coil Technology for MRI System

“…Such a relationship can be useful for building the birdcage with either cylindrical or rectangular conductors with nearly similar performance characteristics. For high field birdcage coils, the authors of this article have presented in a work published elsewhere that a coil that is made of a cylindrical conductor exhibits higher resistance at high field (>3T) imaging frequencies [88]. They also revealed that the RF coil that is made of foil conductors etched on a flexible dielectric substrate (or FPCB) exhibits excellent characteristics on high field MRI applications.…”