• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.7
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• pp.1067-1075
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• 2001

The fields at the aperture of conical horn antenna with corrugations parallel to the axis have been analyzed using FDTD(Finite Difference Time Domain). Easy calculation depending on the change of the structure of antenna and time reduction can be achieved by 2-D FDTD coding with the first-order Mur ABC(absorbing boundary condition). It is confirmed that the corrugation can reduce phase difference of field on aperture. also it is investigated that the directivity is increased by 6.1 %, 12.9%, and 28.4% with one corrugation, two corrugations, three corrugations, respectively. It is also found that the improvement of the characteristics of the antenna is not proportional to the number of the corrugation but more dependent on the location of the corrugation near the aperture than that far the aperture.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.4
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• pp.627-635
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• 2008

Using directional antenna in wireless network can offer many advantages including significant decrease of interference, increase of spatial reuse and possibility of improving network capacity. However, existing 802.11 MAC is designed for use of omni-directional antenna then those advantages can not be shown in that MAC protocol when it uses directional antenna. In this paper, we present a MAC protocol specifically designed for directional antenna to achieve spatial reuse and improve capacity of MAC protocol. Simulation result shows the advantages of our proposal in comparison with existing MAC in terms of end-to-end delay and network throughput.

• Journal of the Korea Society of Computer and Information
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• v.15 no.1
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• pp.111-118
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• 2010

The proposed algorithm to be explained in this paper is the localization technique using directional antenna. Here, it is assumed that anchor node has the ability to transfer the azimuth of each sector using GPS modules, sector antenna, and the digital compass. In the conventional sensor network, the majority of localization algorithms were capable of estimating the position information of the sensor node by knowing at least 3 position values of anchor nodes. However, this paper has proposed localization algorithm that estimates the position of nodes to continuously move with sensor nodes and traveling nodes. The proposed localization mechanisms have been simulated in the Matlab. The simulation results show that our scheme performed better than other mechanisms (e.g. MCL, DV-distance).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.12
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• pp.3608-3613
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• 2009

In this paper, we propose a mobile Radio Frequency Identification antenna for mobile hand set. The proposed antenna with directive radiation characteristics based on combination of electric-magnetic radiators can be installed in the mobile hand-set. The combination of PIFA antenna for electric radiator and loop antenna for magnetic radiator is presented and designed for료 m-RFID reader system. Target frequency band is 900-MHz band. and desired gain is 4dBi. The antenna is simulated using Ansoft HFSS software and shows expected results. The antenna is also manufactured using FR4-epoxy circuit board (h=1 mm, $\varepsilon_{\tau}=4.4$). There are good agreements between the simulated and measured VSWR curves and radiation characteristics.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.35T no.1
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• pp.99-104
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• 1998

It is a good flexibility of bending body and non-interaction of outer bodies for slit antenna to be being studied and developed in this paper. The characteristics of leaked EM waves in slit transmission line are applied to antennas of tele-communication systems. The computer simulations using a special software adapt to design a new slit antenna, and to apply to tele-communications systems with frequencies of land mobile communication (800-900MHz). The good results of which reflection coefficient 511 is 0.21 and directivity is 2.9 and band-widths are 1.5MHz in 851MHz are shown.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.05a
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• pp.203-205
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• 2019

위성항법시스템의 안정적인 정보 제공의 요구사항은 점차 증가하고 있지만, 의도적인 전파교란 및 자연환경에 의하여 성능이 저하된다. eLoran 시스템은 위성항법시스템의 단점을 보완하기위한 대표적인 지상파항법시스템으로 고출력 신호로 의도적인 전파교란에 강인한 장점이 있다. eLoran 시스템에서 사용자는 E-field 또는 H-field 2가지 종류의 수신 안테나를 사용 환경에 따라 적합한 것을 사용한다. 접지가 필요없고 상대적으로 주변 전자장비의 잡음에 강인한 H-field안테나는 두 개의 루프로 구성되어 루프간의 위상과 이득차이로 일정한 원형의 지향성을 가지지 못한다. 그러므로 수신한 신호의 방향에 따라 측정치의 변화가 발생하므로 H-field 안테나를 사용시에는 수신하는 신호의 방향에 따른 오차를 제거해야한다. 본 논문에서는 H-field 안테나와 송신국간의 기하학적 방향오차에 따른 오차를 제거하기 위한 후처리 필터를 제안하였다. eLoran 모의 신호생성기를 활용하여 오차를 분석하고 모델링하여 제거하는 기법을 개발하였다. 제안한 기법을 검증하기 위하여 시뮬레이션과 차량실험을 통하여 오차를 확인하고 제거하여 성능향상을 확인하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.1B
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• pp.15-20
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• 2012

In this paper, an algorithm that enhances the conventional directional CSMA/CA protocol in IEEE 802.15.3c is proposed under saturation environments. For the algorithm, a Markov chain model is presented and analyzed in no-ACK mode. The effects of directional antennas and the features of IEEE 802.15.3c MAC are considered in the model. The optimal sizes of contention window are derived from the numerical results. The numerical results show that the proposed directional CSMA/CA algorithm outperforms conventional one. The overall analysis is verified by simulation. The obtained results provide the criterion for selecting the optimal parameters and developing a MAC protocol that enhances the performance of mmWave WPANs.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.9 s.100
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• pp.926-931
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• 2005

In this paper, the printed-sleeve monopole antenna which has the small size and the broadband characteristics, is presented and its radiation characteristics are investigated. To conform the broadband characteristics of the proposed antenna, the experimental antenna is designed, fabricated, and its radiation characteristics are measured in PCS band (1.75 GHz${\~}$1.87 GHz). It is shown that the designed antenna has the non-directional pattern in the horizontal plane, the directional pattern in the vertical plane, VSWR less than 1.5, and gain in 2.14 dBi${\~}$3.4 dBi. From these results, the proposed antenna is conformed as a broadband antenna which can be used for the mobile communication indoor antenna extensively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.10
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• pp.1097-1106
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• 2009

In this paper, the cross monopole antenna with branch element is presented and its radiation characteristics are investigated. To confirm the broadband characteristics of the proposed antenna, the experimental antenna is designed, fabricated, and its radiation characteristics are measured in PCS, WCDMA, WiBro and S-DMB band(1.750~2.655 GHz). It is shown that the designed antenna has the non-directional pattern in the horizontal plane, the directional pattern in the vertical plane, VSWR less than 1.5 and gain over 1.9 dBi in 1.72~2.82 GHz. From these results, the presented antenna is conformed as a broadband antenna which can be used for PCS, WCDMA, WiBro and S-DMB band.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.10
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• pp.63-71
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• 2009

The patch antennas with an array of pins with excellent radiation characteristics are investigated for several substrate thicknesses. The patch length of a pin array patch antenna for the maximum suppression of radiation in the horizontal plane decreases as the substrate thickness increases. The radiation in the horizontal plane of a pin array patch antenna is very small compared to that of a conventional patch antenna. The increase of forward radiation and the decrease of backward radiation of a pin array patch are obtained compared to those of a conventional patch antenna. The half-power beamwidth of E-plane radiation pattern of a pin array patch antenna is narrow compared to that of a conventional patch antenna so that the directivity is improved.