• Title/Summary/Keyword: dipole array

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A Circularly Polarized Waveguide Narrow-wall Slot Array using a Single Layer Polarization Converter

  • Kim, Dong-Chul;Min, Kyeong-Sik
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.4 no.1
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    • pp.59-65
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    • 2000
  • This paper describes the characteristics of a one dimensional narrow-wall slotted waveguide array with a single-layer linear-to-circular polarization converter consisting of a dipole array. An external boundary value Problem of one slot and three dipoles, which approximates the mutual coupling between the dipole array and an edge slot extending over three faces of a rectangular waveguide, is formulated and analyzed by the method of moments; design of polarization conversion is conducted for this model as a unit element. If every unit element has perfect circular polarization, grating lobes appear in the array pattern due to the alternating slot angle: these are suppressed in this paper by changing the dipole angle and degrading the axial ratio of the unit element. The validity of the design is confirmed by the measurements. The dipole array has negligible effects upon slot impedance; the polarization conversion for existing narrow-wall slotted arrays is realized by add-on dipole array.

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The Crosshole Resistivity Method Using the Mixed Array (혼합배열을 사용하는 시추공간 전기비저항 탐사)

  • Cho In-Ky;Han Sung-Hoon;Kim Ki-Ju
    • Geophysics and Geophysical Exploration
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    • v.5 no.4
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    • pp.250-256
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    • 2002
  • Resistivity tomography has become an important tool to image underground resistivity distribution. This method has been widely applied to site investigation for engineering and environmental purpose. In resistivity tomography, various electrode arrays can be used and each array has both merits and demerits. For example, the pole-pole array has high signal to noise ratio (S/N ratio), but its resolution is too low. The dipole-dipole array has low S/N ratio, but its resolution is very high. The Pole-dipole may has intermediate Snf ratio and resolution. The modified Pole-dipole array, recently proposed, shows reasonable S/N ratio and resolution, which are comparable to the pole-dipole array. These electrode arrays except the pole-pole array, however, have the problem that the apparent resistivity can diverge at some special electrode Positions. Also, the Pole-Pole array may not reflect the doe resistivity of an anomalous body. In this study, we propose a new electrode array, mixed array, where pole-dipole and modified pole-dipole ways are selectively used with the relative positions of current and potential electrodes. The mixed array has the same level of S/N ratio and resolution as the pole-dipole array and the apparent resistivity does not diverge in the receiver hole. Furthermore, the apparent resistivity using the array can reflect the true resistivity of the anomalous body.

Design for Circularly Polarized Microstrip Cross Dipole Array Antenna by Electromagnetic Coupled Technique (전자기적 결합을 이용한 원편파 크로스-다이폴 마이크로스트립 어레이 안테나의 설계)

  • 민경식;임정남;김동철;임학규
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
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    • 2000.11a
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    • pp.369-373
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    • 2000
  • This paper describes a design for microstrip EMC cross dipole array antenna with circular polarization. To realize the wide bandwidth and circular polarization, the electromagnetic-coupled cross dipole is used. To obtain the uniform aperture illumination, offset technique for array is adopted. In 20-element array design, the calculated axial ratio and gain are about 0.1 dB and 9.9 dBi at 12GHz, respectively. The frequency characteristics of a fabricated 20-element array antenna are measured. The calculated results agree well with the measured ones.

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A Study on the Modified Electrode Arrays in Two-Dimensional Resistivity Survey (2차원 전기비저항 탐사를 위한 변형된 전극배열법에 관한 연구)

  • Kim Jung-Ho;Yi Myeong-Jong;Song Yoonho;Chung Seung-Hwan
    • Geophysics and Geophysical Exploration
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    • v.4 no.3
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    • pp.59-69
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    • 2001
  • Five kinds of modified electrode arrays were proposed to overcome the weak points of the commonly used arrays using dipole and/or pole in two-dimensional resistivity surveys. The modified pole-pole array was suggested to overcome the inefficiency caused by distant earthing in pole-pole array. Four kinds of modified arrays using dipole were designed to enhance the signal-to-noise ratio of the conventional dipole-dipole and pole-dipole arrays through boosting up the measured potential difference. In the numerical experiments using the two-dimensional modeling and inversion, the effects of the ambient electrical noise and the resolving power were examined and the results showed the validity of the modified arrays proposed in this study.

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Design for Microstrip Array Antenna with EMC Dipole for Communication Satellite System (EMC 다이폴을 이용한 CS용 마이크로스트립 어레이 안테나의 설계)

  • 민경식;박세현;김동철;임학규;김상태
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 1999.11a
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    • pp.120-123
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    • 1999
  • This paper presents the design method of EMC(Electromagnetic Coupling) microstrip array antenna for CS(Communication Satellite) system. Microstrip dipole antennas are attractive elements owing to the desirable properties such as simplicity, small size and linear polarization. From the optimum simulation results by the FDTD method[1], design parameters such as EMC dipole length, width, height and offset are discussed at 12CHz. The array characteristics of 5-elements and 10-elements array are also presented. By adjusting geometry of model antenna, we can design dual polarization EMC microstrip dipole antenna for CS system. Direction of nam beam is easily tilted by the control of distance between dipole elements.

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Design of V/UHF band Small Dipole Circular Array Active Antenna (V/UHF대역 소형다이폴 원형배열 능동안테나 설계)

  • Ko, Ji-Hwan;Lee, Cheol-Soo;Kim, Kang-Uk;Cho, Young-Ki
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.13 no.1
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    • pp.6-16
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    • 2009
  • For the application to the direction finding(DF) antenna for V/UHF bands, circular active array composed of 9 dipole element has been investigate. For miniaturization of the overall size array, the element has been chosen to be of the top-hat dipole type. For the broadband operation over 20-1300MHz, some number of pin diodes have been inserted in each arms of each dipole element. By employing this type of each element dipole, the effective dipole length can be increased or decreased according as the inserted pin diodes is on or off. The active array antenna has been design to be directly connected to the balanced push full amplifier such that the amplifier may play a role as a balloon and may improve the sensitivity as a receiver as well. The active array antenna has been designed and fabricated. Some experimental results have been presented in comparison with simulated results.

Miniaturization of Log-Periodic Dipole Array Antenna for PS-LTE Service (재난안전 통신망 서비스를 위한 대수 주기 다이폴 배열 안테나의 소형화)

  • Jeon, Hoo-Dong;Heo, Soo-Young;Ko, Ji-Hwan
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.28 no.3
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    • pp.170-176
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    • 2017
  • In this paper, we proposed the miniaturized structure of the Log-Periodic Dipole Array(LPDA) antenna for PS-LTE(Pubic Safety-Long Term Evolution) service. The length of array dipole was shortened by adding a fractal tree element with iteration to the array dipole to miniaturize the LPDA antenna. As the result, the proposed LPDA antenna was reduced up to 25 %, compared a typical LPDA antenna. To validation of the proposed LPDA antenna specification, the proposed LPDA antenna is fabricated using aluminum with 1.5 mm thickness and performances are measured. Comparison between simulation result and experiment shows good agreement.

Design for the Circularly Polarized Microstrip Cross Dipole Array Antenna by Electromagnetic Coupled Technique (전자기 결합기법을 이용한 원편파 마이크로스트립 크로스 다이폴 어레이 안테나의 설계)

  • 민경식;임정남
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.12 no.1
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    • pp.50-57
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    • 2001
  • This paper describes a design for the circularly polarized microstrip EMC cross dipole array antenna with the wide bandwidth. To realize the characteristics of wide bandwidth and circular polarization, the electromagnetic-coupled cross dipole element is proposed. The optimum design parameters of a circularly polarized EMC cross dipole element are calculated by the FDTD and the Ensemble. To obtain the uniform aperture illumination of electric field in an array, offset technique that the cross dipole elements are alternatively arranged on center of the microstrip feed line is adopted. In 20-element array design, the calculated axial ratio and gain are about 0.1dB and 9.9 dBi at 12 GHz, respectively, The frequency characteristics of a fabricated 20-element array antenna are measured. The calculated results agree well with the measured ones.

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Analysis of Magnetic Dipole Moment for a 300-W Solar-Cell Array

  • Shin, Goo-Hwan;Kim, Dong-Guk;Kwon, Se-Jin;Lee, Hu-Seung
    • Journal of Astronomy and Space Sciences
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    • v.36 no.3
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    • pp.181-186
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    • 2019
  • The attitude information of spacecraft can be obtained by the sensors attached to it using a star tracker, three-axis magnetometer, three-axis gyroscope, and a global positioning signal receiver. By using these sensors, the spacecraft can be maneuvered by actuators that generate torques. In particular, electromagnetic-torque bars can be used for attitude control and as a momentum-canceling instrument. The spacecraft momentum can be created by the current through the electrical circuits and coils. Thus, the current around the electromagnetic-torque bars is a critical factor for precisely controlling the spacecraft. In connection with these concerns, a solar-cell array can be considered to prevent generation of a magnetic dipole moment because the solar-cell array can introduce a large amount of current through the electrical wires. The maximum value of a magnetic dipole moment that cannot affect precise control is $0.25A{\cdot}m^2$, which takes into account the current that flows through the reaction-wheel assembly and the magnetic-torque current. In this study, we designed a 300-W solar cell array and presented an optimal wire-routing method to minimize the magnetic dipole moment for space applications. We verified our proposed method by simulation.

Short-Ended Electromagnetically Coupled Coaxial Dipole Array Antenna

  • Kim, Joong-Pyo;Lee, Chang-Won
    • Journal of electromagnetic engineering and science
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    • v.2 no.2
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    • pp.87-92
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    • 2002
  • A short-ended electromagnetically coupled coaxial dipole array antenna is investigated theoretically. The antenna has an advantage of structural simplicity. The integral equations are derived for the proposed structure by use of the Fourier transform and mode expansion, and the simultaneous linear equations are obtained. The slot electric field and strip current are obtained by solving the simultaneous linear equations. The effects of slot and strip numbers on the radiation efficiency, beamwidth and directivity gain of the antenna are presented.