• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.9
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• pp.1975-1984
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• 1997

In this paper, we analyzed the frequency characteristics and the crosstalk of the adjacent parallel lines and the crossed lines in high-speed packaging interconnections by using the three-dimensional finite difference time domain (3D FDTD) method. To analyze the actual crosstalk phenomena in the transmission of the high-speed digital sgnal, the step pulse with fast rise time was used for the source excitation signal instead of using the Gaussian pulse that is generally used in FDTD. To veify the theoretical resutls, the experimental interconnection lines that were fabricated on the Duroid substrate($\varepsilon_{r}$=2.33, h=0.787 [mm]) were tested by TDR(time domain reflectometry). The results show good agreement between the analyzed results and the tested outcomes.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.7
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• pp.1057-1066
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• 2001

This paper describes a design for linear polarization antenna using the EMCD (electromagnetically coupled dipole). The analysis and the design of model antennas are conducted by FDTD method. Vertical and horizontal linear polarizations are easily obtained by variation of dipole position. In 1-element antenna design, mutual coupling between microstrip feed line and radiator is considered. Design parameters of each 1-element antenna with vertical and horizontal polarization are used for array design. Radiation power and main beam tilting angle can be controlled by the offset and the distance between radiating elements in an array, respectively. 5-element array antennas are fabricated and measured to prove the design validity. The results of FDTD simulation and measurement show the reasonable agreement.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.12
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• pp.1412-1415
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• 2012

Return signals of a ground penetrating radar(GPR) for mine detection at various frequencies and soil moisture contents are analyzed in this paper. We first compute the dielectric constant, conductivity and attenuation loss based on clay loam which is Korea standard soil. The mine-detection images of GPR at various frequencies are also obtained using the finite-difference time-domain(FDTD) technique. Then, the signal-to-clutter ratio(SCR) and received power of the radar are studied. It is shown that the variable frequency channels are suitable for a GPR to detect landmines at various soil conditions.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.1958-1964
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• 2016

AC railway feeding system use single phase to supply power to the railway vehicles. And the system use the rail track as a return current path, so that current flows in the rail. In this situation inductive interference on communication system and unsafe environment can appear on railway system. Therefore knowing the current distribution of catenary system and analysing the return current is required. In this study detail return current distribution was analyzed by modeling the catenary system as 4-conductors group. The distribution characteristics and trends of return current were studied by using the PSCAD/EMTDC and FDTD method that based on Maxwell equation was used to calculate the induced voltage. Simulation code was made by MATLAB. Using this study result data, we can suggest the proper installation location of digital device and these data can be used for additional studies related to return current or induced voltage as a base data.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.3
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• pp.45-54
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• 2004

Microwave characteristics of ridge type CPW traveling-wave(TW) electroabsorption modulator and photodetector are affected by the thickness of intrinsic layer, width of guiding layer, and the separation of signal and ground electrodes. These factors are determined effective index of microwave and characteristic impedance due to changing of capacitance(C) and inductance(L) of device. However, conventional equivalent circuit of TW-structure is approximated to microstrip and CPW transmission line by distribution of electric and magnetic fields, respectively. In this paper, we analyzed microwave characteristics of TW-structure and found more accurate value of C and L by using finite difference time domain (FDTD) method. These values are adopted circuit element of equivalent circuit. Microwave characteristics obtained by the FDTD and equivalent circuit model show good agreement.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.3
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• pp.296-304
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• 1998

A design method of an electromagnetic wave absorber with ferrite fins in the second layer, which has very wide band frequency characteristics and is used for single-polarized wave absorption such as TV wave etc, has been designed. To examine the effectiveness of the Equivalent Material Constants Method$(EMCM)^{[1]}$ which is approximate method, the effective complex permittivity calculated by the Hashin-Strikman formulas and the EMCM are compared. Since, furthermore, the reflectivities by the EMCM in space and the FDTD method in an rectangular waveguide agreed well each other, it has been confirmed that the proposed electromagnetic wave absorber has excellent absorption characteristics in the frequency range of 30 MHz to 5830 MHz. Thus, it can be concluded that the EMCM is usefull to design and analyze the electro-magnetic wave absorber proposed here.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.7
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• pp.1065-1073
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• 1999

This paper analyzed the ground bounce caused by the power plane resonance in the multilayered printed circuit board(PCB) using the Haar-wavelet-based Multiresolution Time-Domain (MRTD). In conventional Finite-Difference Time-Domain(FDTD), the highly fine vertical cell is needed to represent the distance between $V_{cc}$ plane and ground plane since the two planes are very close. Therefore the time step $\Deltat$ must be very small to satisfy the stability condition. As a result, a large number of iterations are needed to obtain the response in wanted time. For this problem, this paper showed that the computation time can be reduced by application of the MRTD method. The results obtained by the MRTD agree very well with those by FDTD method and analytic solutions. In conclusion, this paper proved the efficiency and accuracy of MRTD method for analyzing the EMI/EMC problems in PCB.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.6
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• pp.1054-1061
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• 2007

In this paper, the comparison between UPML and Liao's absorbing boundary condition in the FDTD(Finite-Difference Time-Domain) method was performed for the analysis of the 2D cylindrical coordinate system. Generally, it is known as the absorbing characteristics of the UPML is bro than Liao's absorbing boundary condition in the 2D rectangular coordinate. The simulation results in this paper showed that Liao's original absorbing boundary condition is better than other two absorbing boundary conditions, Liao's modified condition and UPML. We concluded that more numerical, theoretical studies, simulations and verifications for various absorbing boundary conditions will be needed to get more accurate results for the design of useful 2D cylindrical microwave circuits.

• ETRI Journal
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• v.21 no.2
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• pp.1-8
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• 1999

We analyze the characteristics of a coaxial-to-waveguide transition based on the finite difference time domain (FDTD) method with the cylindrical to rectangular cell interpolation scheme. The scheme presented in this paper is well suited for the analysis of a microwave device with a probe near waveguide discontinuity because perfect TEM mode can be generated inside the coaxial cable by using the cylindrical cell. The scattering parameters of a designed Ka-band transition are evaluated and compared with those of commercially available software, High Frequency Structure analysis Simulator (HFSS) and measured data. There exists good agreement between the measured and calculated data. In order to prove an accuracy of the interpolation scheme, a coaxial to waveguide transition with a disk-loaded probe is analyzed by the present approach and the results of this analysis are compared with measured data. Comparison shows that our results match very closely to those of measurement and other approaches. The method presented in this paper can be applied to analyze the characteristics of a probe excited cavity, coaxial waveguide T-Junctions, and so on.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.2
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• pp.278-284
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• 2001

In this paper, the slanted metallic boundaries is analyzed for the triangular cell grid method and compared with staircase approximation. Specially, this paper is derived an error range to the angle of inclination between the metal and the dielectric from the triangular cell grid method. That result, when the angle of inclination is from 30˚ to 60˚, the triangular cell grid method improves the accuracy, the computer memory and time requirement in comparison with the staircase approximation. But, out of this range, we do not expect the accuracy because a side of cell size lengthen.