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[Author] Mitsuhiro YOKOTA(7hit)

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  • Scattering of a Three-Dimensional Hermite-Gaussian Beam Mode by a Dielectric Circular Cylinder

    Mitsuhiro YOKOTA  Takashi TAKENAKA  Otozo FUKUMITSU  

     
    LETTER-Electromagnetic Theory

      Vol:
    E69-E No:4
      Page(s):
    317-320

    Scattering of a three-dimensional Hermite-Gaussian beam mode by a dielectric circular cylinder at normal incidence is considered by using the complex-source-point method. The scattered fields are examined numerically for a lowest-order mode.

  • Radio Wave Shadowing by Two-Dimensional Human BodyModel

    Mitsuhiro YOKOTA  Yoshichika OHTA  Teruya FUJII  

     
    PAPER-Antennas and Propagation

      Pubricized:
    2017/07/06
      Vol:
    E101-B No:1
      Page(s):
    195-202

    The radio wave shadowing by a two-dimensional human body is examined numerically as the scattering problem by using the Method of Moments (MoM) in order to verify the equivalent human body diameter. Three human body models are examined: (1) a circular cylinder, (2) an elliptical cylinder, and (3) an elliptical cylinder with two circular cylinders are examined. The scattered fields yields by the circular cylinder are compared with measured data. Since the angle of the model to an incident wave affects scattered fields in models other than a circular cylinder, the models of an elliptical cylinder and an elliptical cylinder with two circular cylinders are converted into a circular cylinder of equivalent diameter. The frequency characteristics for the models are calculated by using the equivalent diameter.

  • Scattering of a Gaussian Beam by Dielectric Cylinders with Arbitrary Shape Using Multigrid-Moment Method

    Mitsuhiro YOKOTA  Kunihiro AOYAMA  

     
    PAPER-Numerical Techniques, Computational Electromagnetic

      Vol:
    E90-C No:2
      Page(s):
    258-264

    Scattering of a Gaussian beam by dielectric cylinders with arbitrary shape is analyzed by using the moment method combined with multigrid method. The effectiveness of the multigrid-moment method is firstly shown from the CPU time and residual norm viewpoints. The effect of the initial value for the multigrid cycle is also considered. After that, the scattered fields by two dielectric convex lens are calculated and the effect of the radius of curvature, width and the distance between each lens on the scattered field is examined.

  • Analysis of Optical Resonator Constructed by Two-Dimensional MDM Plasmonic Waveguide

    Yoshihiro NAKA  Masahiko NISHIMOTO  Mitsuhiro YOKOTA  

     
    BRIEF PAPER-Electromagnetic Theory

      Pubricized:
    2022/09/08
      Vol:
    E106-C No:3
      Page(s):
    103-106

    An efficient bent waveguide and an optical power splitter with a resonator constructed by a metal-dielectric-metal plasmonic waveguide have been analyzed. The method of solution is the finite difference time domain (FD-TD) method with the piecewise linear recursive convolution (PLRC) method. The resonator can be realized by utilizing impedance mismatch at the connection between a narrow waveguide and an input/output waveguide. Numerical results for the bent waveguide show that transmission bands can be controlled by adjusting the length of the narrow waveguide. We have also shown that the optical power of the power splitter is entirely distributed into the output waveguide at the resonant wavelength and its distribution ratio can be controlled.

  • Numerical Examination on Effective Permittivity of Two-Dimensional Multilayered Periodic Structures

    Mitsuhiro YOKOTA  Kazumasa MATSUMOTO  

     
    BRIEF PAPER-Electromagnetic Theory

      Vol:
    E97-C No:12
      Page(s):
    1150-1153

    The effective permittivity of the two-dimensional multilayered periodic structures which consist of the rectangular dielectric cylinders is examined numerically. The original periodic structure is replaced with a simple structure such as the dielectric slab. By using the reflectance of the periodic structure obtained by the FDTD method, the effective permittivity of the dielectric slab, which has the same reflectance as that of the periodic structure, is obtained by using the transcendental equation. In order to reduce the procedure to obtain the reflectance from the multilayered periodic structures, the reflectance from one-layered structure is used. The range of the application and validity of this procedure is examined.

  • Relations and Orthogonality Properties for the Generalized Gaussian Beam Functions

    Mitsuhiro YOKOTA  Shinji AONO  Otozo FUKUMITSU  

     
    LETTER

      Vol:
    E74-C No:9
      Page(s):
    2935-2937

    In this letter, the relations between the generalized beams with the different parameters are investigated by using the formula for the Hermite polynomials and that for the generalized Laguerre polynomials. The adjoint functions for the generalized Laguerre-Gaussian beam functions are also derived concretely. It is shown that the generalized beam is represented by a finite number of another generalized beam with the different parameter.

  • Analysis of Optical Power Splitter with Resonator Structure Constructed by Two-Dimensional MDM Plasmonic Waveguide Open Access

    Yoshihiro NAKA  Masahiko NISHIMOTO  Mitsuhiro YOKOTA  

     
    BRIEF PAPER-Electromagnetic Theory

      Pubricized:
    2023/12/07
      Vol:
    E107-C No:5
      Page(s):
    141-145

    An efficient optical power splitter constructed by a metal-dielectric-metal plasmonic waveguide with a resonator structure has been analyzed. The method of solution is the finite difference time domain (FD-TD) method with the piecewise linear recursive convolution (PLRC) method. The resonator structure consists of input/output waveguides and a narrow waveguide with a T-junction. The power splitter with the resonator structure is expressed by an equivalent transmission-line circuit. We can find that the transmittance and reflectance calculated by the FD-TD method and the equivalent circuit are matched when the difference in width between the input/output waveguides and the narrow waveguide is small. It is also shown that the transmission wavelength can be adjusted by changing the narrow waveguide lengths that satisfy the impedance matching condition in the equivalent circuit.