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Takashi Nagasaka

Bio: Takashi Nagasaka is an academic researcher from Chuo University. The author has contributed to research in topics: Radar cross-section & Boundary value problem. The author has an hindex of 4, co-authored 11 publications receiving 35 citations.

Papers
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Journal ArticleDOI
TL;DR: The H-polarized plane wave diffraction by a thin material strip is analyzed using the Wiener-Hopf technique together with approximate boundary conditions and a far field expression is derived.
Abstract: The H-polarized plane wave diffraction by a thin material strip is analyzed using the Wiener-Hopf technique together with approximate boundary conditions. An asymptotic solution is obtained under the condition that the thickness and the width of the strip are small and large compared with the wavelength, respectively. The scattered field is evaluated asymptotically based on the saddle point method and a far field expression is derived. Scattering characteristics of the strip are discussed via numerical results of the radar cross section.

15 citations

Proceedings ArticleDOI
01 Jan 2014
TL;DR: Nagasaka and Kobayashi as discussed by the authors analyzed plane wave diffraction by a thin material strip for both H and E polarizations using the Wiener-Hopf technique together with the two different approximate boundary conditions.
Abstract: TPID5179783. Volakis analyzed the H-polarized plane wave diffraction by a thin material strip using the dual integral equation approach and the extended spectral ray method together with approximate boundary conditions [1]. In [1], Volakis first solved rigorously the diffraction problem involving a single material halfplane, and subsequently obtained a high-frequency solution to the original strip problem by superposing the singly diffracted fields from the two independent half-planes and the doubly/triply diffracted fields from the edges of the two half-planes. Therefore his analysis is not rigorous from the viewpoint of boundary value problems, and may not be applicable unless the strip width is relatively large compared with the wavelength. In this paper, we shall consider the same problem as in Volakis [1], and analyze plane wave diffraction by a thin material strip for both H and E polarizations using the Wiener-Hopf technique together with the two different approximate boundary conditions [2], [3]. Main results of this paper are published in Nagasaka and Kobayashi [4], [5].

6 citations

Proceedings ArticleDOI
15 Oct 2015
TL;DR: In this article, the E-polarized plane wave diffraction by a thin material strip is analyzed using the Wiener-Hopf technique together with approximate boundary conditions under the condition that the thickness and width of the strip are small and large compared with the wavelength, respectively.
Abstract: The E-polarized plane wave diffraction by a thin material strip is analyzed using the Wiener-Hopf technique together with approximate boundary conditions. An asymptotic solution is obtained under the condition that the thickness and the width of the strip are small and large compared with the wavelength, respectively. The scattered field is evaluated asymptotically based on the saddle point method and a far field expression is derived. Scattering characteristics of the strip are discussed via numerical results of the radar cross section.

4 citations

Proceedings ArticleDOI
05 Jul 2016
TL;DR: In this article, the plane wave diffraction by a thin material strip is analyzed using the Wiener-Hopf technique and approximate boundary conditions and an asymptotic solution is obtained under the condition that the strip width is large compared with the wavelength.
Abstract: The plane wave diffraction by a thin material strip is analyzed using the Wiener-Hopf technique and approximate boundary conditions. An asymptotic solution is obtained under the condition that the strip width is large compared with the wavelength. Applying the saddle point method, the scattered far field is evaluated asymptotically. Numerical results on the radar cross section are presented.

4 citations

Proceedings ArticleDOI
22 Sep 2016
TL;DR: In this article, the plane wave diffraction by a thin material strip is analyzed using the Wiener-Hopf technique and approximate boundary conditions and an asymptotic solution is obtained under the condition that the strip width is large compared with the wavelength.
Abstract: The plane wave diffraction by a thin material strip is analyzed using the Wiener-Hopf technique and approximate boundary conditions. An asymptotic solution is obtained under the condition that the strip width is large compared with the wavelength. Applying the saddle point method, the scattered far field is evaluated asymptotically. Numerical results on the radar cross section (RCS) are presented.

3 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, the analytical scattering of left and right handed Beltrami fields and also TE and TM polarizations from a PEMC strip placed in unbounded chiral medium using Kobayashi potential (KP) method is studied.
Abstract: This paper studies the analytical scattering of left and right handed Beltrami fields and also TE and TM polarizations from a PEMC strip placed in unbounded chiral medium using Kobayashi Potential (KP) method. Initially, the scattered fields are assumed as left and right circularly polarized waves with unknown weighting functions. Then, applying the boundary conditions leads to dual integral equations (DIE). Utilizing the Weber–Schafheitlin's (WS's) discontinuous integrals and Jacobi's polynomials, results in satisfying the DIEs and the edge conditions. In the process, the matrix equations with unknown coefficients are produced. The size of the matrix is truncated with high accuracy and the equations are solved by the matrix algebra. After determining the unknown coefficients, the scattered fields are calculated. The proposed method is validated using convergence analysis and also two various reported methods: Physical Optics (PO) and Method of Moments (MoM). Finally, in order to show the influence of the parameters of the problem, parametric study is presented for different values of: the admittance parameter of PEMC, the width of the strip, chirality parameter and the angle of the incidence. It is notable that the method is greatly accurate and can be applied to the strips with the width of too narrow to wide.

19 citations

Journal ArticleDOI
TL;DR: The H-polarized plane wave diffraction by a thin material strip is analyzed using the Wiener-Hopf technique together with approximate boundary conditions and a far field expression is derived.
Abstract: The H-polarized plane wave diffraction by a thin material strip is analyzed using the Wiener-Hopf technique together with approximate boundary conditions. An asymptotic solution is obtained under the condition that the thickness and the width of the strip are small and large compared with the wavelength, respectively. The scattered field is evaluated asymptotically based on the saddle point method and a far field expression is derived. Scattering characteristics of the strip are discussed via numerical results of the radar cross section.

15 citations

Journal ArticleDOI
TL;DR: In this article, the generalized Wiener-Hopf method was extended to handle piecewise constant inhomogeneous dielectric layers by resorting to the characteristic Green's function procedure starting from the wave equation.
Abstract: In this article, we present a new methodology in spectral domain to study a novel, complex canonical electromagnetic problem constituted of perfectly electrically conducting (PEC) wedges immersed in complex environments. In particular, we present an arbitrarily flanged dielectric-loaded waveguide that resembles practical structures in scattering analysis, radar applications, antenna’s design, and electromagnetic compatibility. The proposed method is based on the recently developed semianalytical method known as the generalized Wiener–Hopf technique that extends the applicability of classical Wiener–Hopf method to a new variety of problems constituted of different geometries and materials. In this article, the method is further extended and it is now capable of handling piecewise constant inhomogeneous dielectric layers by resorting to the application of characteristic Green’s function procedure starting from the wave equation. The method has the benefit to be a comprehensive mathematical model and to be quasi-analytical, thus allowing us to investigate the true physics of the problem in terms of field’s components. The proposed solution is also of interest in computational electromagnetics to benchmark numerical codes. Validation through numerical results is reported in terms of engineering quantities such as geometrical theory of diffraction (GTD)/uniform theory of diffraction (UTD) coefficients, total far fields, and modal fields.

14 citations

Journal ArticleDOI
01 Feb 2021-Optik
TL;DR: In this article, the Kobayashi potential (KP) method is applied to the PEMC strip and diffraction of electromagnetic wave from the proposed strip is assessed by Kobaya potential method which yields exact answer.

7 citations