• Title/Summary/Keyword: dipole array

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4-Sector Circular Array Dipole Antennas with Beam Steering for Wireless LAN Communications (4 섹터 지향성 절환 원형 배열 다이폴 안테나)

  • 이종녕;김기채;양규식
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2000.05a
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    • pp.115-118
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    • 2000
  • 본 논문에서는 4 개의 다이폴 소자로 구성한 4 섹터 지향성 절환 원형 배열 다이폴 안테나의 기본 특성을 검토하고 있다. 안테나의 방사 지향성이 순차적으로 4 섹터 절환이 가능하도록 하기 위해 급전 및 무급전 소자를 적절히 이용하고 있으며, 무급전 소자의 유도 전류에 의한 원형 배열 안테나의 특성 개선을 위해 급전 소자를 제외한 나머지 소자들을 단락 또는 개방시켜 방사 지향성 및 이득 특성 등을 계산하고 있다.

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Compensation of Radiation Pattern Distortion by Mutual Coupling in the Array Antenna Using the Particle Swarm Optimization Algorithm (입자군집 최적화 알고리즘을 이용한 배열안테나의 상호결합에 의한 방사패턴 왜곡보상)

  • Kim, Jae Hee;Ahn, Chi-Hyung;Chun, Joong-Chang
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.9 no.5
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    • pp.458-464
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    • 2016
  • This paper proposes the compensation method which decreases the radiation pattern distortion caused by the mutual coupling in an array antenna. If the element distance of an array antenna decreases, the radiation pattern could be distorted by the strong mutual coupling, which changes the magnitude and phase of input signals and causes an unwanted radiation pattern. To remove the pattern distortion, compensated input signals are inserted in an array antenna. The magnitude and phase of input signals are determined by Particle Swarm Optimization (PSO) algorithm. A $4{\times}1$ dipole array antenna with omnidirectional elements is used to confirm the validity of the algorithm, where each element is placed in 0.2 wavelength to evoke the strong coupling. After input signals are optimized by PSO, it is found that the compensated radiation results in the same as the ideal case.

Design of the Dual-Band Electrical Beam Tilting Array Antenna with Bi-Directional Directivity (양방향 지향성을 갖는 이중 대역 전기적 빔 틸팅 배열 안테나 설계)

  • Jeon, Hoo-Dong;Heo, Soo-Young;Ko, Ji-Hwan
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.27 no.7
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    • pp.612-619
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    • 2016
  • In this paper, a dual band electrical beam tilting array antenna with bi-directional directivity is designed. Radiating element operates at dual-resonance frequencies and is designed as planar dipole using PCB. In order to tilt the main beam, the phase delay line is designed by use of only the phase shifting line of a $50\Omega$ microstrip line for broadband. The designed antenna has tilting angle of $0^{\circ}$ to ${\pm}8^{\circ}$. For validation of the designed antenna specification, the array antenna is fabricated and the performances are measured. Comparison between theory and experiment shows good agreement.

Design of the Frequency Selective Surface with Transformation of Linear-to-circular Polarization (원편파 변환 주파수 선택 반사기 설계)

  • Ko, Ji-Whan;Cho, Young-Ki
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.38 no.1
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    • pp.34-42
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    • 2001
  • The new periodic array structure or frequency selective surface with polarizers characteristic is proposed. The present structure is constructed with two sheets or FSS material, spaced about one-eight wavelength apart, the dipole element orientations of the two sheets being almost perpendicular to each other. The methods of the spectral domain immittance and MoM are used to analyze electromagnetic scattering from this periodic array structure. To confirm the validity of the polrizer's functions or the new periodic array structure, frequency selective surfaces are fabricated, calculated values for the frequency response of the reflection and transmission loss are compared with measured values. Good correspondence has been observed between them. Good axial ratio has been also observed to be achieved in the proposed structure.

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Broadband multimode antenna and its array for wireless communication base stations

  • Wu, Rui;Chu, Qing-Xin
    • ETRI Journal
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    • v.41 no.2
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    • pp.167-175
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    • 2019
  • A wideband dual-polarized antenna coupling cross resonator is proposed for LTE700/GSM850/GSM900 base stations. An additional resonance is introduced to obtain strong coupling between the dipole and resonator. Moreover, the input impedance of the proposed antenna is steadily close to $50{\Omega}$, which results in better impedance matching. Therefore, a wide bandwidth can be achieved with multiresonance. A prototype is fabricated to verify the proposed design. The measured results show that the antenna has a fractional bandwidth of 35.7% from 690 MHz to 990 MHz for ${\mid}S_{11}{\mid}$ < -15 dB. Stable radiation patterns as well as gain are also obtained over the entire operating band. Moreover, a five-element antenna array with an electrical downtilt of $0^{\circ}$to $14^{\circ}$ is developed for modern base station applications. Measurement shows that a wide impedance bandwidth of 34.7% (690 MHz to 980 MHz), stable HPBW (3-dB beamwidth) of $65{\pm}5^{\circ}$, and high gain of $13.8{\pm}0.6dBi$ are achieved with electrical downtilts of $0^{\circ}$, $7^{\circ}$, and $14^{\circ}$.

Design of an Ultra-Wideband LPDA Antenna for the Feeder of an Airborne Spinning Direction-Finding Reflector Antenna (공중 회전 방향탐지 반사판 안테나 급전기용 초광대역 LPDA 안테나 설계)

  • Park, Young-Ju;Park, Dong-Chul
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.27 no.7
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    • pp.653-659
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    • 2016
  • This paper proposes an ultra-wideband Log-Periodic Dipole Array(LPDA) antenna for the feeder of a reflector antenna to be used for airborne spinning direction-finding and detecting wideband signals. To obtain the ultra-wideband characteristics over the 20:1 bandwidth from S to Ka band, the radiation elements of the antenna were printed on a substrate and a wedge-typed dielectric supporter with robust structure was inserted between the substrates. Also, the center portion of the supporter was replaced by a styrofoam material to reduce the supporter weight. The 5-dB return loss of the designed LPDA antenna showed ultra-wideband characteristics, which are 37.57:1(1.09~40.95 GHz) in the simulation and 33.85:1(1.31~44.35 GHz) in the measurement. We achieved the required gains of 5.78 dBi in the simulation and 5.76 dBi in the measurement in the operating band. The proposed robust, light-weight, and ultra-wideband LPDA antenna confirmed that it can be applied for airborne applications.

Verification of Reinforcement with Grouting Materials in Reservoir Dike using Electrical Resistivity Tomography (전기비저항 토모그래피를 이용한 저수지 제체 그라우팅 효과 검증)

  • Song, Sung-Ho;Yong, Hwan-Ho;Lee, Gyu-Sang;Woo, Myung-Ha
    • 한국지구물리탐사학회:학술대회논문집
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    • 2006.06a
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    • pp.73-78
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    • 2006
  • To verify reinforcing effect of grouting materials on the water leakage region in dike, we performed various hydraulic test and we also applied electric resistivity survey including electrical resistivity tomography(ERT) to see resistivity variation before and after grouting. As the results of dipole-dipole array survey along dike, resistivity distribution after grouting was without noticeable spatial variation. Long term resistivity monitoring results at dike with Schlumberger array electric resistivity survey showed that the decreasing region of apparent resistivity and one dimensional inversion results were the occupied region by grout after grouting. From the ERT using check holes to inspect the effect of grouting, we could find that the ERT is quite effective to evaluate spatially grout region in dike.

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Experimental verification for prediction method of anomaly ahead of tunnel face by using electrical resistivity tomography

  • Lee, Kang-Hyun;Park, Jin-Ho;Park, Jeongjun;Lee, In-Mo;Lee, Seok-Won
    • Geomechanics and Engineering
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    • v.20 no.6
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    • pp.475-484
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    • 2020
  • The prediction of the ground conditions ahead of a tunnel face is very important, especially for tunnel boring machine (TBM) tunneling, because encountering unexpected anomalies during tunnel excavation can cause a considerable loss of time and money. Several prediction techniques, such as BEAM, TSP, and GPR, have been suggested. However, these methods have various shortcomings, such as low accuracy and low resolution. Most studies on electrical resistivity tomography surveys have been conducted using numerical simulation programs, but laboratory experiments were just a few. Furthermore, most studies of scaled model tests on electrical resistivity tomography were conducted only on the ground surface, which is a different environment as compared to that of mechanized tunneling. This study performed a laboratory experimental test to extend and verify a prediction method proposed by Lee et al., which used electrical resistivity tomography to predict the ground conditions ahead of a tunnel face in TBM tunneling environments. The results showed that the modified dipole-dipole array is better than the other arrays in terms of predicting the location and shape of the anomalies ahead of the tunnel face. Having longer upper and lower borehole lengths led to better accuracy of the survey. However, the number and length of boreholes should be properly controlled according to the field environments in practice. Finally, a modified and verified technique to predict the ground conditions ahead of a tunnel face during TBM tunneling is proposed.

Resistivity Tomography in an Inclined Borehole to Surface Purvey Using a Pole-dipole Array (단극-쌍극자 배열을 이용한 경사시추공-지표 탐사에서 전기비저항 토모그래피)

  • Park Jong-Oh;Kim Hee-Joon;Park Chung-Hwa
    • The Journal of Engineering Geology
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    • v.16 no.3 s.49
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    • pp.255-263
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    • 2006
  • In an electrical tomographic survey using an inclined borehole with a pole-dipole array, we must consider several factors: a singular point associated with zero potential difference, a spatial discrepancy between electrode and nodal point in a model due to a inclined borehole, and a variation of geometric factors in connection with a irregular topography. Singular points which are represented by the normal distance from current source to the ground surface can be represented by serveral regions due to a irregular topography of ground surface. The method of element division can be applied to the region in which the borehole is curved, inclined or the distance between the electrodes is shorter than that of nodal points, because the coordinate of each electrode cannot be assigned directly to the nodal point if several electrodes are in an element. Test on a three-dimensional (3-D) synthetic model produces good images of conductive target and shoves stable convergence.

A Bayesian Approach to Geophysical Inverse Problems (베이지안 방식에 의한 지구물리 역산 문제의 접근)

  • Oh Seokhoon;Chung Seung-Hwan;Kwon Byung-Doo;Lee Heuisoon;Jung Ho Jun;Lee Duk Kee
    • Geophysics and Geophysical Exploration
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    • v.5 no.4
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    • pp.262-271
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    • 2002
  • This study presents a practical procedure for the Bayesian inversion of geophysical data. We have applied geostatistical techniques for the acquisition of prior model information, then the Markov Chain Monte Carlo (MCMC) method was adopted to infer the characteristics of the marginal distributions of model parameters. For the Bayesian inversion of dipole-dipole array resistivity data, we have used the indicator kriging and simulation techniques to generate cumulative density functions from Schlumberger array resistivity data and well logging data, and obtained prior information by cokriging and simulations from covariogram models. The indicator approach makes it possible to incorporate non-parametric information into the probabilistic density function. We have also adopted the MCMC approach, based on Gibbs sampling, to examine the characteristics of a posteriori probability density function and the marginal distribution of each parameter.