• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.353-356
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• 2005

There have been many researches on the antenna performance degradation with the presence of the human body around the antenna structure to accomodate personal communication service [1][2]. To better understand the human body effects on the antenna resonance, radiation pattern, and input impedance, simulation was carried out with changing of the distance between antenna and lossy material. Effects on the antenna performance by the surrounding materials are also important in the case of the RFID system. It is desirable that the tag antennas for RFID system must reveal isotropic radiation pattern as well as attain the good impedance matching. In this paper, we investigated the antenna resonance and input impedance characteristic when there exist a lossy material sphere near various types of antenna at 900 MHz. In short antenna resonance was mostly affected by lossy material in the case of a rectangular loop antenna, and impedance variation was smallest in the case of a halfwave dipole.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.9
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• pp.950-954
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• 2003

This paper presents the delivered power and reflection coefficient in metallic shielding enclosure excited by the interior source, which are evaluated with the method of moments, and describes a method for reducing the radiation of electromagnetic fields in the cavity by putting lossy dielectric material in one inside wall. In this paper we introduce carbon polystyrene-foam as lossy dielectric material and observe it's effects of reduction when the thickness and permittivity of lossy dielectric material are changed. The results show that the reduction of the electromagnetic radiation can be achieved by controlling the amount of carbon in lossy dielectric material. The theoretical analysis is verified by the measured delivered power.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.936-942
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• 2009

This paper presents the delivered power and reflection coefficient in metallic shielding enclosure with a sub-cavity, which are evaluated with the method of moments, sad describes a method for controlling the resonance characteristics of the metallic cavity by putting lossy dielectric material in the sub-cavity. In this paper we introduce carbon polystyrene-foam as lossy dielectric material and observe it's effects of reduction when the dimensions of the sub-cavity and permittivity of lossy dielectric material are changed. The results show that the reduction of the electromagnetic radiation can be achieved by controlling the amount of carbon in lossy dielectric material and the dimensions of the sub-cavity. The theoretical analysis is verified by the measured delivered power.

• Journal of electromagnetic engineering and science
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• v.13 no.3
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• pp.158-164
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• 2013

This paper expands a previously proposed optimized higher order (2, 4) finite-difference time-domain scheme (H(2, 4) scheme) for use with lossy material. A low dispersion error is obtained by introducing a weighting factor and two scaling factors. The weighting factor creates isotropic dispersion, and the two scaling factors dramatically reduce the numerical dispersion error at an operating frequency. In addition, the results confirm that the proposed scheme performs better than the H(2, 4) scheme for wideband analysis. Lastly, the validity of the proposed scheme is verified by calculating a scattering problem of a lossy circular dielectric cylinder.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.12
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• pp.1384-1393
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• 2008

In this paper, we analyzed the multilayer structure with lossy metamaterials using ABCD Matrix method to get the transmission characteristics. Compared to the recursive method which cannot be used to analyze the lossy characteristics of multilayer structure because of its complexity, we used the ABCD matrix method is easy to apply because of its matrix chain concepts for arbitrary number of multilayer structure and lossy material. To verify the results of this paper, we used both for multilayer dielectric and metamaterial, respectively, and obtained the same results. Multilayer structure with lossy metamaterial showed minimized ripple and broadband transmission compared to dielectric multilayered structure. This can be used in various applications as antenna radome and shielding material, etc.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.105-109
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• 1987

A solution which combines ray and aperture integration(AI) techniques is presented for the problem of electromagnetic plane wave scattering by an open-ended, perfectly-conducting, semi-infinite parallel plate waveguide with a thin, uniform layer of lossy or absorbing material on its inner walls, and with a simple planar termination inside. Numerical results are given for the fields outside the waveguide.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.3
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• pp.225-232
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• 2018

This paper proposed the optimization method of the extremely low numerical-dispersion finite-difference time-domain (ELND-FDTD) method based on the H(2,4) scheme for wideband and extremely accurate electromagnetic properties of lossy material, which has a constant conductivity and relative permittivity. The optimized values of three variables are calculated for the minimum numerical dispersion errors of the proposed FDTD method. The excellent accuracy of the proposed method is verified by comparing the calculated results of three different FDTD methods and the analytical results of the two-dimensional dielectric cylinder scattering problem.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2315-2317
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• 2005

In this paper, an iterative method to model the electromagnetic heating of electrically large lossy dielectrics is presented. Frequency domain finite element (FEM) solutions of the wave equation are determined for the lossy inhomogeneous dielectric as the material properties are change with temperature and time. The power absorbed from microwave losses is applied to a finite element time domain (FETD) calculation of the heat diffusion equation. Time steps appropriate for updating the piecewise material properties in the wave equation and the time stepping of the heat equation are presented. The effects of preheating and source frequency are investigated.

• Journal of the Korean Institute of Telematics and Electronics
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• v.11 no.4
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• pp.25-29
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• 1974

In this paper, a surfer wide-band FM lossy-line discriminator is investigated, as it has the merit of rediucing the dimensions of the discriminator by using proper dielectric material in the transmission tine. It is shown that the lossy-line discriminator that is made of a pair of the transmission lines satisfying the distortionless condition approximately gives almost no more deterioration in its characteristics than the ideal-line FM discriminator, while the dimensions of the transmission lines of the discriminator can be reduced greatly.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2553-2555
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• 1999

The paper contains design formulas and an execution algorithm for calculation of distributed parameters as well as wave and impedance parameters of a uniform transmission line using data of the line input impedance measurements by the OPEN-SHORT method. In difference from published before works on the OPEN-SHORT method application for line parameters determination, in which the lines with small losses are considered /1-3/, the obtained formulas allow to calculate parameters of transmission lines with arbitrary losses. It opens new possibilities of the OPEN-SHORT method utilization for development and application of the probe - type lossy dielectric media parameters meters based on transmission lines, including probe-type moisture material meters.