• Title/Summary/Keyword: 다이폴

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More compact rectangular two stepped slot antenna for Wi-Fi dual band application (더욱 소형화된 와이파이 이중대역용 직사각형 2단 계단식 슬롯 안테나)

  • Kim, Min-woo;Lee, Yeong-min;Lee, Hee-jae;Lee, Young-soon
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.21 no.6
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    • pp.17-23
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    • 2021
  • In the present study, a more compact dual-band slot antenna is newly proposed for Wi-Fi application. The proposed antenna is composed of rectangular two stepped slot with open end which can generate standing wave resonance at dual frequency bands and L-type microstrip feed line. The measured impedance bandwidths are 50 MHz(2.412 ~ 2.470 GHz) at low frequency band and 452 MHz(5.451 ~ 5.903 GHz) at high frequency band respectiviely. Furthermore its size of 14 × 21 mm2 is reduced by 30% compared to the size of 20 × 21 mm2 of a conventional similar compact slot antenna. It has the omni-directional radiation pattern characteristics of a typical dipole antenna on the H-Plane, so it is suitable for commercial wireless network applications such as Wi-Fi.

Shielding Effectiveness Analysis of the Digital Module Storage Cabinet for Nuclear Power Plants According to the Internal Structure and the Angle of EM wave Incidence (내부구조와 전파 입사각에 따른 원전용 디지털 모듈 보관 캐비닛의 차폐효과 분석)

  • Youn, Sang-Woon;Jang, Do-Young;Choo, Ho-Sung;Kim, Young-Mi;Lee, Jun-Yong
    • The Journal of the Korea institute of electronic communication sciences
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    • v.16 no.1
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    • pp.1-8
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    • 2021
  • In this paper, the cabinet shielding effectiveness (SE) including digital modules for nuclear power plants is analyzed depending on the internal structure and electromagnetic (EM) wave incidence angle. To analyze the SE, the cabinet and modules are modeled using the FEKO EM simulation tool. The SE is then obtained by comparing the electric field with and without the cabinet. In addition, the cabinet SE is observed by changing various conditions such as the spacing of each digital module, incidence angle, and the polarization of the EM wave at the 2.4 G[Hz frequency. To verify the results, the dipole antenna for SE measurements is fabricated, and the SE is measured in a semi-anechoic chamber. The result demonstrates that the SE by the cabinet structure can be expected to be higher when the polarization of the incident EM wave is horizontal to the ground and the distance between the digital modules is wide.

Triple Folded Omnidirectional Microstrip Antenna for GBAS (GBAS용 3중 폴디드 무지향성 마이크로스트립 안테나)

  • Ju, Dae-Keun;Woo, Jong-Myung
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.20 no.4
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    • pp.83-94
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    • 2021
  • In this paper, we proposed a microstrip antenna (center frequency 118 MHz) with an omnidirectional radiation pattern that can replace the antennae used in VDB systems in GBAS. First, to obtain an omnidirectional radiation pattern from a microstrip antenna, we constructed a folded antenna. We then designed a miniaturized triple-folded antenna using perturbation effects. Thus we obtained suitable characteristics with a S11 of -13.91dB, -10 dB bandwidth of 1.5 MHz (1.27%) in the center frequency of 118 MHz. Furthermore, in the yz-plane and xy-plane, the component exhibits an omnidirectional radiation pattern, and the size of the antenna achieves miniaturization of 64.2% compared to the reference antenna. Finally, it is suitable as an antenna for VDB systems in GBAS.

Impact of IODM and ENSO on the East Asian Monsoon: Simulations through NCAR Community Atmospheric Model (동아시아 몬순 지역에서 IODM과 ENSO의 영향 : NCAR Community Atmospheric Model을 이용한 모의 실험)

  • Oh J.-H.;Chaudhari H. S.;Kripalani R. H.
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.7 no.4
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    • pp.240-249
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    • 2005
  • The normal Indian Ocean is characterized by warmer waters over the eastern region and cooler waters over the western region. Changes in sea surface temperature (SST) over the western and eastern Indian Ocean give birth to a phenomenon now referred to as the Indian Ocean Dipole Mode (IODM). The positive phase of this mode is characterized by positive SST anomalies over the western Indian Ocean and negative anomalies over the southeastern Indian Ocean, while the negative phase is characterized by a reversed SST anomaly pattern. On the other hand, the normal Pacific Ocean has warm (cool) waters over the western (eastern) parts. Positive (negative) SST anomalies over the central/eastern (western) Pacific Ocean characterize the E1 Nino phenomenon. The reverse situation leads to the La Nina phenomenon. The coupled ocean-atmosphere phenomenon over the Pacific is referred to as the E1 Nino Southern Oscillation (ENSO) phenomenon. In this study the impact of IODM and ENSO on the East Asian monsoon variability has been studied using observational data and using the Community Atmospheric Model (CAM) of the National Center for Atmospheric Research (NCAR). Five sets of model experiments were performed with anomalous SST patterns associated with IODM/ENSO superimposed on the climatological SSTs. The empirical and dynamic approaches reveal that it takes about 3-4 seasons fur the peak IODM mode to influence the summer monsoon activity over East Asia. On the other hand, the impact of ENSO on the East Asian monsoon could occur simultaneously. Further, the negative (positive) phase of IODM and E1 Nino (La Nina) over the Pacific enhances (suppresses) monsoon activity over the Korea-Japan Sector. Alternatively, IODM appears to have no significant impact on monsoon variability over China. However, El Nino (La Nina) suppresses (enhances) monsoon activity over China. While the IODM appears to influence the North Pacific subtropical high, ENSO appears to influence the Aleutian low over the northwest Pacific. Thus, the moisture supply towards East Asia from the Pacific is determined by the strengthening/weakening of the subtropical high and the Aleutian low.

Broadband U-Shaped RFID Tag Antenna with Near-Isotropic Characteristic (광대역에서 일정한 준 등방성 특성을 가지는 U-형태의 RFID 태그 안테나)

  • Lee, Sang-Woon;Jung, Hak-Joo;Choo, Ho-Sung;Park, Ik-Mo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.20 no.5
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    • pp.480-492
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    • 2009
  • In this paper, we proposed a broadband U-shaped RFID tag antenna with near-isotropic characteristic at UHF band. The proposed tag antenna is composed of the U-shaped half wavelength dipole and a rectangular shaped feed. The rectangular shaped feed that is located inside U-shaped dipole is connected for conjugate impedance matching with the commercial tag chip. A better constant gain deviation characteristic in the operating frequency band is achieved by inserting a rectangular slit in the lower center of the U-shaped antenna body. On the condition of VSWR<2, the tag antenna had the measured bandwidth of 10.36%, from 860.5 to 954.5 MHz, and 9.84%, from 864.5 to 954 MHz, for antenna without slit and with slit, respectively. On the condition of VSWR<5.8, the tag antennas had the measured bandwidth of 15.78%, from 835.5 to 979.5 MHz, and 15.89%, from 837 to 981.5 MHz, for antenna without slit and with slit, respectively. The difference between the maximum and minimum gain deviations of tag antenna without slit in the operating frequency band is 0.53 dB since the maximum and minimum gain deviations are 3.86 dB and 3.33 dB, respectively. Whereas the difference between the maximum and minimum gain deviations of tag antenna with slit in the operating frequency is 0.06 dB since the maximum and minimum gain deviations are 3.60 dB and 3.54 dB, respectively.

Comparative Analysis of Effective RCS Prediction Methods for Chaff Clouds (효과적인 채프 구름의 RCS 예측 방법 비교 분석 연구)

  • Kim, Min;Lee, Myung-Jun;Lee, Seong-Hyeon;Park, Sung-ho;Kong, Young-Joo;Woo, Seon-Keol;Kim, Hong-Rak;Kim, Kyung-Tae
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.29 no.3
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    • pp.233-240
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    • 2018
  • Radar cross section (RCS) analysis of chaff clouds is essential for the accurate detection and tracking of missile targets using radar. For this purpose, we compare the performance of two existing methods of predicting RCS of chaff clouds. One method involves summing up the RCS values of individual chaffs in a cloud, while the other method predicts the RCS values using aerodynamic models based on the probability density function. In order to compare and analyze the two techniques more precisely, the RCS of a single chaff computer-aided design model consisting of a half wavelength dipole was calculated using the commercial electromagnetic numerical analysis software, FEKO 7.0, to estimate the RCS values of chaff clouds via simulation. Thus, we verified that our method using the probability density distribution model is capable of analyzing the RCS of chaff clouds more efficiently.

U-Shaped Broadband RFID Tag Antenna with a Parasitic Element (기생소자를 가지는 U-형태의 광대역 RFID 태그 안테나)

  • Lee, Sang-Woon;Cho, Chi-Hyun;Lee, Kee-Keun;Choo, Ho-Sung;Park, Ik-Mo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.20 no.1
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    • pp.75-82
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    • 2009
  • In this paper, we proposed a U-shaped broadband RFID tag antenna with a parasitic element operating at UHF band. The proposed tag antenna consists of a U-shaped half wavelength dipole antenna and an inverse U-shaped parasitic element inside the U-shaped dipole antenna. In order to have good impedance matching, the commercial tag chip is attached to the lower center of the rectangular shaped feed. On the condition of VSWR<2, the tag antenna had the measured bandwidth of 4.96 % from 882 to 927 MHz and showed the gain deviation of less than 3.16 dB. On the condition of VSWR<5.8, the tag antenna satisfies the worldwide UHF RFID bandwidth and is showed the gain deviation of less than 5.07 dB. The minimum gain deviation characteristic appears near the center of bandwidth which minimizes variation of gain deviation characteristic with respect to the frequency.

Study on a broadband quasi-Yagi antenna for mobile base station (이동통신 기지국용 광대역 quasi-Yagi 안테나에 관한 연구)

  • Lee, Jong-Ig;Yeo, Jun-Ho
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.9
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    • pp.4165-4170
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    • 2012
  • In this paper, a method for the improvement in the gain and bandwidth of a microstrip-fed broadband planar quasi-Yagi antenna (QYA) is studied. The broadband characteristics of the QYA are achieved from the coplanar strip-fed planar dipole driver and a parasitic director close to the driver. In order to obtain stable gain variation over the required frequency band, a director and a ground reflector are appended to the driver having a nearby parasitic director. The QYA is fed through an integrated balun composed of a microstrip line and a slot line which are terminated in a short circuit. By adjusting the feeding point, a broadband impedance matching is obtained. A QYA with an operating frequency band of 1.75-2.7 GHz and a gain > 4.5 dBi is designed and fabricated on an FR4 substrate with dielectric constant of 4.4 and thickness of 1.6mm. The experimental results show that the fabricated antenna has good performance such as a broad bandwidth of 59.7%(1.55-2.87 GHz), a stable gain between 4.7-6.5 dBi, and a front-to-back ratio > 10 dB. The measured data agree well with the simulation, which validates this study.

Spatial Audio Signal Processing Technology Using Multi-Channel 3D Microphone (멀티채널 3차원 마이크를 이용한 입체음향 처리 기술)

  • Kang Kyeongok;Lee Taejin
    • The Journal of the Acoustical Society of Korea
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    • v.24 no.2
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    • pp.68-77
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    • 2005
  • The purpose of a spatial audio system is to give a listener an impression as if he were present in a recorded environment when its sound is reproduced. For this purpose a dummy head microphone is generally used. Because of its human-like shape, dummy head microphone can reproduce spatial images through headphone reproduction. However, its shape and size are restriction to public use and it is difficult to convert the output signal of dummy head microphone into a multi-channel signal for multi-channel environment. So, in this paper, we propose a multi-channel 3D microphone technology. The multi-channel 3D microphone acquire a spatial audio using five microphones around a horizontal plane of a rigid sphere and through post processing, it can reproduce various reproduction signals for headphone, stereo, stereo dipole, 4ch and 5ch reproduction environments. Because of complex computation, we implemented H/W based post processing system. To verily the Performance of the multi-channel 3D microphone, localization experiments were Performed. The result shows that a front/back confusion, which is the one of common limitations of conventional dummy head technology, can be reduced dramatically.

Optimization Design in Time Domain on Impulse GPIR System (임펄스 GPIR시스템의 시간영역 최적화 설계)

  • Kim, Kwan-Ho;Park, Young-Jin;Yoon, Young-Joong
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.46 no.3
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    • pp.32-39
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    • 2009
  • In this paper, system optimization design technique of an impulse ground penetrating image radar (GPIR) in time domain is proposed to improve depth resolution of the system. For the purpose, time domain analysis method of key components such as impulse generator and UWB antenna is explained and by simulation, parameters of each component are determined. In particular, by standardizing the impulse signal, spectrum efficiency of a radiated impulse signal is improved and a U-shaped planar dipole antenna for a UWB antenna is developed. By equipping a parabolic metal reflector with the proposed antenna, external noise is prevented and the ability of radiating an input impulse into ground is improved. In addition, to remove ringing effect of the propose antenna which causes serious degradation of the system performance, resistors are loaded at the edge of the antenna and then Tx and Rx UWB antennas are optimized by simulation in time domain. For images of targets buried under the ground migration technique is applied and influence of tough ground surface on distortion of received impulse signals is reduced using technique of noise and signal distortion reduction in time domain and its time resolution is enhanced. To verify the design optimization procedure, a prototype of an GPIR and an artificial test field are made. Measurement results show that the resolution of the system designed is as good as that of a theoretical model.