IEEE Antennas and Propagation Society International Symposium 1997. Digest最新文献_第6页

A tunable second-resonance cross-slot antenna 一种可调谐的二次谐振交叉槽天线

IEEE Antennas and Propagation Society International Symposium 1997. Digest Pub Date : 1997-07-13 DOI: 10.1109/APS.1997.630066

M. Forman, Z. Popovic

引用次数: 17

An anisotropic perfectly matched layer-absorbing medium in finite element time domain method for Maxwell's equations 麦克斯韦方程组的有限元时域法中各向异性完美匹配层吸收介质

IEEE Antennas and Propagation Society International Symposium 1997. Digest Pub Date : 1997-07-13 DOI: 10.1109/APS.1997.631552

V. Mathis

{"title":"An anisotropic perfectly matched layer-absorbing medium in finite element time domain method for Maxwell's equations","authors":"V. Mathis","doi":"10.1109/APS.1997.631552","DOIUrl":"https://doi.org/10.1109/APS.1997.631552","url":null,"abstract":"When we try to solve Maxwell's equations by a numerical method like the finite difference or finite element, one of the major question is: how to close the calculus domain? This is a mathematical question. Another point of view is: how to simulate an anechoic chamber in order not to be disturbed by reflections of the waves. The first way to answer this question was to use absorbing boundary conditions. Sacks et al. (see IEEE Trans. Antenna Propag., vol.43, no.l2, p.1460-3, 1995) present an approach for deriving a perfectly matched layer (PML) for mesh truncation. This approach is based on using anisotropic material properties to describe the absorbing layer. They have shown that the material properties of the medium can be chosen such that a planar interface between the anisotropic medium and free-space is perfectly reflectionless. This approach offers the advantage that it does not require a modification of Maxwell's equations and it is very easy to implement in finite elements. Sacks et al. present a formulation in frequency domain. We present the use of this approach in the finite element time domain.","PeriodicalId":283897,"journal":{"name":"IEEE Antennas and Propagation Society International Symposium 1997. Digest","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133721397","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

Exact and asymptotic analysis of an infinite grid of metal strips using G1DMULT 用G1DMULT对金属条的无限网格进行精确和渐近分析

IEEE Antennas and Propagation Society International Symposium 1997. Digest Pub Date : 1997-07-13 DOI: 10.1109/APS.1997.631518

S. Raffaelli, Z. Šipuš, P. Kildal, M. Johansson

引用次数: 0

The effect of an air gap on the radiation pattern of a microstrip leaky wave antenna radiating into a half space 气隙对微带漏波天线半空间辐射方向图的影响

IEEE Antennas and Propagation Society International Symposium 1997. Digest Pub Date : 1997-07-13 DOI: 10.1109/APS.1997.631757

L. McMillan, N. Shuley

引用次数: 5

Calculation of SAR and B/sub 1/-field within human head excited by MRI birdcage coils 磁共振鸟笼线圈激发人体头部SAR和B/sub - 1/-场的计算

IEEE Antennas and Propagation Society International Symposium 1997. Digest Pub Date : 1997-07-13 DOI: 10.1109/APS.1997.631780

J. Chen, J. Jin

{"title":"Calculation of SAR and B/sub 1/-field within human head excited by MRI birdcage coils","authors":"J. Chen, J. Jin","doi":"10.1109/APS.1997.631780","DOIUrl":"https://doi.org/10.1109/APS.1997.631780","url":null,"abstract":"Birdcage coils have been widely used to generate radiofrequency (RF) pulses for magnetic resonance imaging (MRI) because of their capability to produce a highly homogeneous B/sub 1/-field over a large volume within the coil. This is true even if the coil is loaded with a human body or a human head provided that the frequency of the B/sub 1/-field is low (less than 50 MHz). However, when birdcage coils are employed for high frequency MRI, the interaction between the electromagnetic (EM) field and the biological object to be imaged deteriorates the B/sub 1/-field homogeneity. Such a deterioration reduces the quality of the MR images and causes difficulties for advanced MRI studies such as functional MRI and MR spectroscopy. Moreover, the EM interaction at high frequencies also leads to an increased electric field, thus, an increased specific energy absorption rate (SAR) in the biological object, causing concern about the possible adverse effects of MRI on human health. Jin et al. (see Phys. Med. Biol., vol.41, p.2719-38, 1996) proposed a method that was suitable for modelling open MRI coils; however, it has difficulties in modelling coils with an RF shield, which is often used to reduce the unwanted interactions between the EM fields and the exterior structures. We employ the finite-difference time-domain (FDTD) method to study this problem. It is found that the FDTD method can effectively model the complex anatomical structure of the human head, the currents in the MRI coil, and the RF shield.","PeriodicalId":283897,"journal":{"name":"IEEE Antennas and Propagation Society International Symposium 1997. Digest","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114443121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Focal plane beam synthesis method for dielectric lens antennas 介质透镜天线焦平面波束合成方法

IEEE Antennas and Propagation Society International Symposium 1997. Digest Pub Date : 1997-07-13 DOI: 10.1109/APS.1997.631590

K.K. Chan, M. Gimersky, R. Pokuls

引用次数: 1

2D and 3D finite element modeling of electrical machines 电机的二维和三维有限元建模

IEEE Antennas and Propagation Society International Symposium 1997. Digest Pub Date : 1997-07-13 DOI: 10.1109/APS.1997.631816

J. Sabonnadiere, A. Foggia

引用次数: 0

Design and breadboarding of a compact and tuningless triplexer for satellite applications 用于卫星应用的紧凑型无调谐三工器的设计和面包板

IEEE Antennas and Propagation Society International Symposium 1997. Digest Pub Date : 1997-07-13 DOI: 10.1109/APS.1997.631863

L. Accatino, B. Piovano, G. Vercellino, R. Ravanelli

引用次数: 1

Optically controlled scanning antennas comprising a plasma grating 包括等离子光栅的光学控制扫描天线

IEEE Antennas and Propagation Society International Symposium 1997. Digest Pub Date : 1997-07-13 DOI: 10.1109/APS.1997.631785

V. Manasson, V. A. Yepishin

引用次数: 1

Moving vehicle range profiles measured using a noise radar 使用噪声雷达测量移动车辆的距离轮廓

IEEE Antennas and Propagation Society International Symposium 1997. Digest Pub Date : 1997-07-13 DOI: 10.1109/APS.1997.625539

E. Walton, I. Theron, S. Gunawan, L. Cai

引用次数: 25