2005 Fiscal Year Final Research Report Summary
Imaging of effective medium parameters of random medium contaioning many particles
| Project/Area Number |
15560370
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Measurement engineering
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| Research Institution | Sasebo National College of Technology |
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Principal Investigator |
NANBU Yukihisa Sasebo National College of Technology, Associate Professor, 電気電子工学科, 助教授 (00228115)
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| Co-Investigator(Kenkyū-buntansha) |
MITSUHASHI Kazuhiko Sasebo National College of Technology, Associate Professor, 電気電子工学科, 助教授 (60311114)
TAKAHIRA Hideaki Sasebo National College of Technology, Lecturer, 電気電子工学科, 講師 (80249896)
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| Project Period (FY) |
2003 – 2005
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| Keywords | effective medium parameters / multiple scattering method / Electromagnetic wave propagation / effective constitutive parameters / random medium / chiral medium |
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| Research Abstract |
Materials in nature have been used to design many kinds of electromagnetic devices or functional elements, while artificial materials are studied in order to develop more sophisticated devices. One of them has been proposed by mixing many particles. In the future utilization, it will become more important to examine electromagnetic properties of them at high frequencies. This means that multiple scattering of waves between particles plays a central role in the determination of material properties. One of important parameters to know the electromagnetic properties of the composite material is the effective propagation constant of the medium. They have been obtained through several approaches. However, most researches have dealt with simple composite medium of particles having just one kind of property or symmetry shaped like a sphere or a cylinder. If materials are composed of particles with several kinds of properties and/or with complex shapes, the composite materials are expected to
… More
possess more interesting characteristics. The following are conclusions in our research.
(1)We have analyzed the effective constitutive parameters for a random medium in which many chiral spheres are distributed by using our approach. The approach is based on an unconventional multiple scattering method by which wave scattering can be systematically treated in a medium whose dielectric particles are randomly displaced from a uniformly ordered spatial distribution. The effective constitutive parameters are estimated by changing the volume fraction, dielectric constant and chirality of the chiral spheres. The results were compared with those of the random medium with dielectric spheres to make clear the characteristics of the effective constitutive parameters of the chiral random medium.
(2)We assumed a composite medium containing pairs of chiral or dielectric spheres (aggregate spheres) and numerically evaluated the effective propagation constant of the medium. For chiral materials, it was common to discuss its characteristics by decomposing into the left- and right-handed polarizations. First, we obtained a T-Matrix of the aggregate sphere by using recursive algorithm. Second, multiple scattering equations with the T-Matrix are solved by applying Effective Field Approximation (EFA) to estimate the effective propagation constants for left- and right-handed polarizations. The characteristics of the effective propagation constants was made clear by changing the electromagnetic properties of particles. Less
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