• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.4
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• pp.21-26
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• 2019

In this paper, TE(transverse electric) scattering problems by a resistive strip grating between a double dielectric layer are analyzed by using the PMM(point matching method) known as a numerical method of electromagnetic fileld. The boundary conditions are applied to obtain the unknown field coefficients, the scattered electromagnetic fields are expanded in a series of Floquet mode functions, and the resistive boundary condition is applied to analysis of the resistive strip. The numerical results for the normalized reflected and transmitted power are analyzed by according as the width and spacing of resistive strip, the relative permittivity and thickness of the double dielectric layers, incident angles, and uniform resisitivity. Typically, the reflected power for the conductive strip increased as the value of the relative dielectric constant increased, the reflected power for the resistive strip with uniform resistivity decreased as the value of the resisvivity increased. The numerical results for the presented structure of this paper are shown in good agreement compared to those of the existing papers.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.2
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• pp.47-52
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• 2019

In this paper, TE(transverse electric) scattering problems by a conductive strip grating between a double dielectric layer are analyzed by applying the FGMM(Fourier-Galerkin moment method) known as a numerical method of electromagnetic fileld. The boundary conditions are applied to obtain the unknown field coefficients, and the conductive boundary condition is applied to analysis of the conductive strip. The numerical results for the normalized reflected and transmitted power are analyzed by according as the width and spacing of conductive strip, the relative permittivity and thickness of the double dielectric layers, and incident angles. Generally, as the value of the dielectric constant increases, the reflected power increases and the transmitted power decreases, respectively. As the dielectric constant increases, the current density induced in the strip increases as it goes to both strip ends. The numerical results for the presented structure of this paper are shown in good agreement compared to those of the existing papers.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.3
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• pp.71-76
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• 2023

In this paper, TE(transverse electric) scattering problems by a resistive strip grating between a grounded double dielectric layer are analyzed by applying the FGMM(fourier galerkin moment method) known as a numerical method of electromagnetic fileld. The boundary conditions are applied to obtain the unknown field coefficients, the scattered electromagnetic fields are expanded in a series of Floquet mode functions, and the resistive boundary condition is applied to analysis of the resistive strip. Overall, as the resistivity decreased, the magnitude of the current density induced in the resistive strip increased, and the reflected power also increased. In case of uniform resistivity, the reflected power decreased as the relative permittivity of the dielectric layers increased or the thickness of the dielectric layer increased. The numerical results for the presented structure in this paper are shown in good agreement compared to those of the existing papers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.11A
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• pp.883-890
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• 2003

In this paper, Electromagnetic scattering problems by a resistive strip grating with tapered resistivity on a grounded dielectric plane according as strip width and spacing, relative permittivity and thickness of dielectric layers, and incident angles of a electric wave are analyzed by applying the FGMM(Fourier-Galerkin Moment Method) Known as a numerical procedure. The scattered electromagnetic fields are expanded in a series of floguet mode functions. The boundary conditions are applied to obtain the unknown field coefficients and the resistive boundary condition is used for the relationship between the tangential electric field and the electric current density on the strip. The tapered resistivity of resistive strips varies zero resistivity at strip edges. Then the induced surface current density on the resistive strip is expanded in a series of Chebyshev polynomials of the second kind. The numerical results of the geometrically in this paper are compared with those for the existing uniform resistivity and perfectly conducting strip. The numerical results of the normalized reflected power for conductive strips case with zero resistivity in this paper show in good agreement with those of existing paper.

• Journal of Advanced Navigation Technology
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• v.10 no.2
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• pp.152-158
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• 2006

In this paper, electromagnetic scattering problems by a resistive strip grating with zero resistivity at the strip-edges on a grounded 2 dielectric layers according as strip width and spacing, relative permittivity, thickness of dielectric layers, and incident angles of a electric wave are analyzed by applying the FGMM(Fourier-Galerkin Moment Method) known as a numerical procedure. The scattered electromagnetic fields are expanded in a series of floguet mode functions. The boundary conditions are applied to obtain the unknown field coefficients and the resistive boundary condition is used for the relationship between the tangential electric field and the electric current density on the strip. The tapered resistivity of resistive strips varies zero resistivity at strip edges. Then the induced surface current density on the resistive strip is expanded in a series of Chebyshev polynomials of the second kind. The normalized reflected power with zero resistivity in this paper show in good agreement with those of existing paper.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.1
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• pp.37-44
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• 2020

This study investigated the microstructure and piezoelectric properties of lead-free 0.74(Bi_1/2Na_1/2)TiO₃-0.26SrTiO₃ (BNST26) piezoelectric ceramics sintered using a microwave furnace. For comparison, specimens were also prepared using a conventional furnace sintering (CFS). Average grain sizes of 2.4 ㎛ and 3.2 ㎛ were obtained in the sample sintered at 1,100℃ for 5 min using microwave sintering (MWS) and at 1,175℃ for 2 h using CFS, respectively. To quantify the changes in the microstructures and electrical properties according to the sintering conditions, the polarization hysteresis, bipolar and unipolar strain curves, and temperature dependence of permittivity were evaluated. As a result, it was determined that the P_max (maximum polarization), P_r (remanent polarization) and S_max (maximum strain) values tend to increase with the average grain size. Based on these results, it is concluded that the MWS method can produce lead-free ceramics with superior performance in a relatively short time compared to the conventional CFS method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.10
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• pp.1005-1011
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• 2011

In this paper, we present a marching-on-in-degree(MOD) finite difference method(FDM) based on the Helmholtz wave equation for analyzing transient electromagnetic responses in a general dispersive media. The two issues related to the finite difference approximation of the time derivatives and the time consuming convolution operations are handled analytically using the properties of the Laguerre functions. The basic idea here is that we fit the transient nature of the fields, the flux densities, the permittivity with a finite sum of orthogonal Laguerre functions. Through this novel approach, not only the time variable can be decoupled analytically from the temporal variations but also the final computational form of the equations is transformed from finite difference time-domain(FDTD) to a finite difference formulation through a Galerkin testing. Representative numerical examples are presented for transient wave propagation in general Debye, Drude, and Lorentz dispersive medium.

• Journal of the Korean Vacuum Society
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• v.7 no.3
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• pp.229-236
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• 1998

In this paper, thin films of Polyimide (PI) were fabricated by vapor deposition polymerization method (VDPM) of dry processes. The film's properties with curing temperature and electrical properties were studies. The synthesis of hexafluoroisopropyliden-2,2-bis[phthalic anhydride](6FDA) and 4, 4'-diamino diphenyl ether (DDE) was carried out by vapor deposition polymerization(VDP) with the same deposition rate. The evaporation temperature of 6FDA and DDE were $214^{\circ}C$ and $137^{\circ}C$, respectively, so as to preserve balance of stoichiometry. The polymic acid (PAA) made by VDPM were changed to PI by thermal curing. The uniformity and density of PI thin films were increased according to increasing curing temperature. The relative permittivity and dissipation loss factor were 3.7 and 0.008 at the frequency of 100Hz~200KHz, respectively, for the fabricated in the curing temperature of $300^{\circ}C$. Also, the resistivity was about 1.05$\times$$ 10^{15}$$\Omega$cm at $30^{\circ}C$.

• Journal of Advanced Navigation Technology
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• v.15 no.3
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• pp.349-354
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• 2011

In this paper, H-polarized scattering problems by a resistive strip grating with zero resistivity at strip-edges over a grounded dielectric plane according to the strip width and grating period, the relative permittivity and thickness of a dielectric layer, and incident angles of a transverse electric (TE) plane wave are analyzed by applying the Fourier-Galerkin Moment Method (FGMM). The tapered resistivity of resistive strips has zero resistivity at strip edges, then the induced surface current density on the resistive strip is expanded in a series of Chebyshev polynomials of the second kind as a orthogonal ploynomials. The sharp variations of the reflected power are due to resonance effects were previously called wood's anomallies, the numerical results for the reflected power are compared with those of uniform resistivity in the existing papers.

• Journal of Advanced Navigation Technology
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• v.17 no.4
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• pp.429-434
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• 2013

In this paper, the TM (Transverse Magnetic) scattering problems by a perfectly conducting strip grating over a grounded two dielectric layers with edge boundary condition are analyzed by applying the FGMM (Fourier Galerkin Moment Method). For the TM scattering problem, the induced surface current density is expected to the very high value at both edges of the strip, then the induced surface current density on the conductive strip is expanded in a series of the multiplication of the Chebyshev polynomials of the first kind and the functions of appropriate edge boundary condition. Generally, when the value of the relative permittivity of dielectric layers over the ground plane increased, the strip width according to the sharp variation points of the reflected power is shifted to a higher value. The numerical results shown the fast convergent solution and good agreement compared to those of the existing papers.