• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.4
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• pp.386-392
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• 2002

This paper presents a basic characteristics of 4-element circular array dipole antennas for 4-sector beam steering. The coupled integral equations for the unknown current distributions on dipole elements are derived and solved by applying Galerkin's method of moments. The parasitic elements have been used to increase the directional gain and the beam is steered electronically either by sswitching between the parasitic elements or switching the position of the active element. The parasitic elements are switched short-circuited or open-circuited as required to steer a directional beam. In order to verify the theoretical analysis, the radiation pattern was compared with experiments.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.1
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• pp.37-44
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• 2009

In this paper, a TRS band(Trunked Radio System: $806{\sim}866\;MHz$) array antenna has a good front-to-back ratio characteristics for the mobile communication base station is proposed. The proposed array antenna is composed of the $5{\times}3$ radiated elements which are the microstrip dipole antennas with the cavity-backed reflector. For the validity of the proposed antenna, the $5{\times}3$ array antenna is designed, fabricated, and its radiation characteristics are measured. As a result of measurements, the antenna gain is over 13.3 dBi and the front-to-back ratio is over 40 dB at the useable frequency band. We confirm that the designed antenna can be used as the mobile communication base station antenna with the excellent back lobe characteristics.

• Geomechanics and Engineering
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• v.19 no.1
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• pp.93-104
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• 2019

Anomalies and/or fractured grounds not detected by the surface geophysical and geological survey performed during design stage may cause significant problems during tunnel excavation. Many studies on prediction methods of the ground condition ahead of the tunnel face have been conducted and applied in tunneling construction sites, such as tunnel seismic profiling and probe drilling. However, most such applications have focused on the drill and blast tunneling method. Few studies have been conducted for mechanized tunneling because of the limitation in the available space to perform prediction tests. This study aims to predict the ground condition ahead of the tunnel face in TBM tunneling by using an electrical resistivity tomography survey. It compared the characteristics of each electrode array and performed an investigation on in-situ tunnel boring machine TBM construction site environments. Numerical simulations for each electrode array were performed, to determine the proper electrode array to predict anomalies ahead of the tunnel face. The results showed that the modified dipole-dipole array is, compared to other arrays, the best for predicting the location and condition of an anomaly. As the borehole becomes longer, the measured data increase accordingly. Therefore, longer boreholes allow a more accurate prediction of the location and status of anomalies and complex grounds.

• Geophysics and Geophysical Exploration
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• v.1 no.2
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• pp.92-100
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• 1998

Array CSAMT surveys were conducted in two areas where it was not easy to identify the presence of faults only with geological survey because of thick overburden. The purpose of these surveys were to locate the faults and to delineate the deep resistivity structures around the faults. The steep dip lineaments having high contrast in resistivity laterally and the low resistive zones having some width in the resistivity sections were interpreted as faults and fracture zones associated with faults, respectively, The good applicability of array CSAMT to the investigation of fault was recognized owing to the agreement between the interpretation results of array CSAMT and the conclusive evidences collected by the following geological survey. The evidences includes the recent exposure of fault and the trajectory of fault evidences of the survey line. A comparison of the applicabilities of array CSAMT method and the resistivity method using dipole-dipole array was presented with the results of both methods along a same traverse line.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.7
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• pp.800-806
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• 2008

In this paper, a wide-band dipole antenna suitable for use in PCS/WCDMA/WiBro($1.750{\sim}2.39\;GHz$) base station array antenna is presented. The presented antenna is a dipole antenna with pate which has the reflector element and improves the gain flatness. To confirm the wide-band characteristics and the gain flatness of the presented antenna, the experimental antenna is fabricated and its radiation characteristics are measured, compared with calculated results. It is shown that the designed antenna has VSWR less than 1.5, gain over 5 dBi, and gain flatness 0.74 dB in $1.75{\sim}2.39\;GHz$. The measured results show good agreement with the calculated results. From these results, we confirm that the designed antenna can be used as a array element of the wide-band base station array antenna for PCS/WCDMA/WiBro.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.2
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• pp.21-26
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• 2022

In this paper, we investigated the effect of tilting and bending of an 2.45GHz ISM band embroidered dipole array antenna due to the human body movement. The antenna characteristics showed larger variations in tilting on the X-axis than the Y-axis. The antenna gain varied by 0.25[dB] when the antenna tilted by 3.5°. As tilting angle increased the operating frequency(f_o) showed decreasing tendency and the return loss(S₁₁) showed increasing tendency. The antenna characteristics also showed more variation in bending on the X-axis than the Y-axis. As bending the antenna the antenna characteristics affected much more in bending on the X-axis than the Y-axis. The antenna gain varied by 3.73[dB] as the curvature(1/R_rad) increased by 0.04[mm^-1]. As it bended more the operating frequency(f_o) showed decreasing and then increasing tendency and the return loss(S₁₁) showed increasing tendency.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.6
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• pp.43-55
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• 2013

In this paper, we propose a cylindrical active phased array antenna of Beam Steering Characteristics in the horizontal plane(H-plane) and vertical plane(E-Plane) on the cylinder form array structure. We design the bent dipole antenna of the cylindrical array structure adapted excellent mutual-coupling characteristics, designed and manufactured the cylindrical array antennas and power combiner/divider unit for power dividing and combining on the antenna. The radiating elements array spacing of Cylindrical array antenna were determined to avoid grating lobes at half power beam steering. Beam steering of the antenna was implemented with 6-bit phase shifter in the transceiver and have been designed based on the characteristics the antenna beam steering at -24 degrees to 24 degrees horizontal, vertical 0 degrees to 36 degrees beam steering. A cylindrical active phased array antenna that produced for verification the performance of the antenna are measured radiation characteristics in accordance with beam steering at L-Band.

• Journal of electromagnetic engineering and science
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• v.2 no.2
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• pp.128-131
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• 2002

A circular polarizer structure of a reflection type, which consists of two sheets of photoetched diople array, is investigated theoretically and experimentally.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.12
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• pp.1027-1035
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• 2016

In this paper, the method to miniaturize the radiating element of a VHF-band active electronically scanned array is proposed. The length of the proposed dipole having trapezoidal shape structure is miniaturized using meander line while the performance degradation is minimized. The grid reflector is used to improve the antenna directivity and insensitivity due to the outer environment. In addition, the antenna is designed to take into account for array application. The fabricated antenna has a 9.1 % fractional bandwidth for the voltage standing wave ratio(VSWR) 2:1 and the maximum gain of 4.24 dBi. The front-to-back ratio(FBR) is larger than 15 dB.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.2
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• pp.19-29
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• 2004

In this paper, the beam steering dipole phased array antenna systems for IMT-2000 base station have been designed. The designed beam steering dipole phased array antenna systems are constituted by the antenna part and the beam steering control system part. The antenna part is designed by the proposed flat dipole for the broadband characteristics, and the 8${\times}$8 dipole way antenna is constructed by the Proposed flat dipole for the directional radiation pattern. Besides the vertical Power divider is designed for the vertical power distribution. The beam steering control system part is designed the horizontal power divider for the horizontal power distribution, the 4-bit phase shifters and the driving circuit of phase shifters for the horizontal beam tilting. In order to evaluate a performance of the designed antenna systems, they were fabricated and the radiation characteristics were measured. From the measured results, we found that the horizontal beams were tilted by the each control signals, and the measured radiation characteristics showed good agreement with the design goals.