• The Journal of Korean Institute of Communications and Information Sciences
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• v.14 no.4
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• pp.321-328
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• 1989

The propagation characteristics of dielectric waveguides has been analyzed by finite element method. We have proposed the finite element formutation of the variational expression in the three-component magnetic field based on Galerkin's method which seek for the propagation constant by a given value of frequency. In this approach, the divergence relation for H is satisfied and spurious modes does not appear and finite element solustions agree with the exact solutions. In order to varify the validity of the present method the numerical results for a rectangular waveguide partilly filled with dielectric are compared with other results.

• Journal of Electrical Engineering and information Science
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• v.2 no.5
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• pp.114-120
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• 1997

A design method is newly presented for the creation of planar type filters which shapes will be nonuniform transmission line with continuously varying characteristic impedances. Those filters yield frequency characteristics of the bandstop filter in transmission, and have not nay discontinuities. The design is achieved by the control of wave propagation in view to both reflection an transmission properties on the dispersive nonuniform line within the desired frequency band. The developed algorithm is based on optimized perturbations of inherent nulls of lobes from the solution of first-order nonlinear differential equation for reflection coefficients of the nonuniform line, and an appropriate distribution of reflection coefficient which affects to filter length and bandwidth. Practical measurements for designed wideband microstrip and stop filter show very good agreement with theoretical results.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2004.01a
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• pp.1-226
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• 2004

I. Title APMC'03(2003 Asia Pacific Microwave Conference) II. Objecuve $\bigcirc$Investigation of new trend in the field of microwave engineering $\bigcirc$Establishment of R＆D track for wireless and high speed communication III. Scope of investigation $\bigcirc$R＆D trend in various microwave engineering areas-Solid state Devices and circuits-Electromagnetic Field Theory-EMI＆EMC-Phased ＆ Active Array Antennas-Scattering ＆ Propagation $\bigcirc$Discussions with various technical topics-New research ＆ development topics-Establishment of wireless ＆ high speed communications IV. Results During the conference, very active academic exchange were possible between Korean and foreign microwave engineering scholars. It was also possible to introduce the level and activities of Korean microwave engineering researches to foreign countries. Also, it was good opportunity to contact foreign scholars and researchers for valuable academic discussion using technical paper presentations and inquiries.

• Journal of the Korean Institute of Telematics and Electronics
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• v.11 no.4
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• pp.1.2-4
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• 1974

Effects of nonreciprocal microwave propagation upon the width and height of a thin slab of transversely magnetized N-Si loaded in a rectangular waveguide are observed experimentally at the room temperature and the experimental results have been analysed qualitatively.

• Electronics and Telecommunications Trends
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• v.15 no.1 s.61
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• pp.38-40
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• 2000

자동 요금 징수 시스템인 ETC(Electronic Toll Collection) 시스템에서 차량의 탑재장치와 비컨(Beacon) 간에 마이크로파가 전파되는 경로를 모델화하였으며 다중 경로에 따른 페이딩 효과를 분석하였다. 또한 환경 변화 즉 강우 시 마이크로파 전파도 고려하여 수치분석을 하였다. 분석결과 강우에 의한 반사면의 반사계수가 변하여 페이딩 효과가 크게 증가하였다. 이런 수치해석 결과를 탑재장치에서 수신된 전압의 크기와 비컨과 차량 사이의 거리로 도시하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.2 s.93
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• pp.228-234
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• 2005

A magnetic composite as noise absorber of quasi-microwave band was developed. The Fe-Si-Al alloy powder were forged by attrition mill to get flaky shape. The magnetic composite sheet was fabricated in which powders are dispersed in polymer and aligned in the direction perpendicular to electromagnetic wave propagation. The permittivity of magnetic composite is increased as forging time increasing, while the permeability is decreased slightly. The maximum attenuation peak of reflection loss is shifted to lower fiequency range as milling time increasing, and the value of maximum attenuation peak is to get smaller gradually. From these result, we could designed a noise absorber sheet (t=1.0 mm) for quasi-microwave band, which is impedance matched at 1.4 GHz with respect to -8.2 dB reflection 1055.

• Journal of Internet Computing and Services
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• v.21 no.2
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• pp.19-26
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• 2020

This paper analyses the feasibility of using implantable antennas to detect and monitor tumors. We analyze this setting according to the wireless propagation loss and signal fading produced by human bodies and their environment in an indoor scenario. The study is based on the ITU-R propagation recommendations and prediction models for the planning of indoor radio communication systems and radio local area networks in the frequency range of 300 MHz to 100 GHz. We conduct primary estimations on 915 MHz and 2.4 GHz operating frequencies. The path loss presented in most short-range wireless implant devices does not take into account the human body as a channel itself, which causes additional losses to wireless designs. In this paper, we examine the propagation through the human body, including losses taken from bones, muscles, fat, and clothes, which results in a more accurate characterization and estimation of the channel. The results obtained from our simulation indicates a variation of the return loss of the spiral antenna when a tumor is located near the implant. This knowledge can be applied in medical detection, and monitoring of early tumors, by analyzing the electromagnetic field behavior of the implant. The tumor was modeled under CST Microwave Studio, using Wisconsin Diagnosis Breast Cancer Dataset. Features like the radius, texture, perimeter, area, and smoothness of the tumor are included along with their label data to determine whether the external shape has malignant or benign physiognomies. An explanation of the feasibility of the system deployment and technical recommendations to avoid interference is also described.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.1
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• pp.89-95
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• 1997

X-cut y-propagation $LiNbO_{3}$ optical modulator is analyzed by finite element calculation. the purpose of this trial is the design of wide-bandwidth x-cut $LiNbO_{3}$ optical modulator with ridge wave guide, which was only applied to z-cut $LiNbO_{3}$ optical modulator. the simulation tool is examined by the comparison between our results and Becker's. And we consider the optimum position of optical waveguide to electrodes for decreasing the driving voltage. The calculated driving-voltage, characteristic impedance and microwave effective index at $1.3{\mu}{\textrm{m}}$ optical wavelength are 18 V.cm, $48.13{\Omega}$ and 2.168, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.5A
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• pp.696-701
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• 2000

Electronic Toll Collection (ETC) System makes the telecommunication possible between the Beacon and the On Board Unit(OBU) for automatic toll collection. In this paper, the propagation path of microwave is modelled and the induced voltage of receiving antenna is analyzed numerically according to multi-path fading effect. In our modelling, we consider frequency, weather condition, polarization and antenna radiation pattern. Also, we suggest the diversity technique in order to reduce the fading effect. In the resuts, the fading effect is reduced significantly in case of the vertical polarization at the rain condition. In general the circular polarization is the most desirable in this application. The antenna which has the high directivity, is also desirable. Using the space and frequency diversity technique at the Beacon, the fading effect is reduced effectively. These results are compared with our experimental data.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.8
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• pp.1621-1628
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• 2003

Packaging structures to block the propagation of higher­order modes in the shielded microstrip lines are designed. Packaging for microwave circuits is necessary, basically, to isolate and protect circuits from outside environments both physically and electrically. The drawback of packaging is the possibility of higher­order mode propagation, similar to waveguide modes, as the operating frequency increases. One of Possible choices for the higher­order mode suppression is to insert diaphragms to the housing structure. The shielding effects of diaphragms are analyzed using an FEM code. Several parameters such as dispersion, mode conversion, and higher­order mode transmission and reflection are analyzed. The effect of higher­order mode suppression is eminent as the depth or width of a diaphragm is increased in the air region of the microstrip line. It is shown that inductive diaphragm structure can lower ${S_21}$ for the second­order mode incidence by 30㏈, comparing with the conventional capacitive diaphragm structure. Packaging structure analyzed in this paper can be applied usefully to the design of the microwave system in a package such as transmit/receive modules.