Electromagnetic Field Analysis of a Dipole Coil Element With Surface Impedance Characterized Shielding Plate for 7-T MRI
Electromagnetic Field Analysis of a Dipole Coil Element With Surface Impedance Characterized Shielding Plate for 7-T MRI
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DOI：
10.1109/tmtt.2016.2518168
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发表时间：
2016-03-01
影响因子：
4.3
通讯作者：
Rennings, Andreas
中科院分区：
文献类型：
--
作者：
Chen, Zhichao;Solbach, Klaus;Rennings, Andreas
在本文中，我们系统地研究了电磁场的带状线偶极子线圈单元的各种屏蔽板，其特征在于表面阻抗。初始分析是基于一个2-D有限元法模型，其中所考虑的表面阻抗进行了分类的幅度和相位。研究表明，如果考虑绝对电磁场分布，屏蔽板可以近似地用复表面阻抗的大小来模拟。此外，随着表面阻抗的大小增加，由带状线激发的磁场和电场倾向于以更宽的方式分布。因此，带状线线圈的场的横向均匀性可以通过具有高表面阻抗的屏蔽板来改善，这已经通过基于单线圈元件和多线圈元件的3-D模型来验证。对于实验验证，两个屏蔽板镀铜基板和高阻抗表面，表现出一个小的和大的表面阻抗，分别被认为是。数值模拟和测量之间的场分布的一个很好的协议已被观察到。
In this paper, we systematically investigate the electromagnetic (EM) field of a stripline dipole coil element backed by various shielding plates, which are characterized by surface impedance. The initial analysis is based on a 2-D finite-element-method model, where the considered surface impedance was categorized in terms of magnitude and phase. It has been demonstrated that the shielding plate can be approximately modeled by the magnitude of a complex surface impedance if the absolute EM field distribution is considered. Additionally, as the magnitude of the surface impedance increases, the magnetic and electric fields excited by the stripline tend to distribute in a broader manner. Thus, the transversal homogeneity of the field of a stripline coil can be improved by a shielding plate with a high surface impedance, which has been verified by 3-D models based on single-and multi-coil elements. For the experimental validation, two shielding plates-a copper-plated substrate and a high-impedance surface, which exhibits a small and large surface impedance, respectively-are considered. An excellent agreement of field distributions between numerical simulation and measurement has been observed.