• 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 Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.1
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• pp.33-39
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• 2008

In this paper, a broadband rectangular reflector antenna with 16-array elements for WiBro/WiMAX band(2.3${\sim}$3.5 GHz) is designed, and its radiation characteristics are investigated. The designed antenna is composed of the IBBD(Integrated Balun Bow-tie Dipole) elements and has the feed circuit at the rear of the reflector to reduce the unwanted electromagnetic wave from it. To confirm the broadband characteristics of the designed antenna, test antenna is fabricated and its radiation characteristics are measured, compared with calculated results. The measured results show good agreement with the calculated results. As a result of measurements, 1.8GHz of bandwidth(VSWR<1.6) is achieved at $2.06{\sim}3.89GHz$ and the antenna gain over 10.3 dBi. We confirm that the designed antenna can be used as a broadband antenna for WiBro/WiMAX.

• Journal of the Korea Convergence Society
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• v.6 no.5
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• pp.249-255
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• 2015

In this paper, we present an azimuth error analysis for the correlative interferometer direction finding. The correlative interferometer is a direction finding method that compares the theoretical and measured phase differences. The direction of the radio transmitter can be estimated by obtaining the maximum correlation between two data sets. We used a 5-element circular array antennas arranged in a circle. To derive the correlation function between antenna elements, we assume that the incident plane wave arrives from a certain angle and the phase difference of each antenna can be derived by comparing with the reference. The suggested direction finding gives a relatively accurate result even if the radio transmitter is located in the higher altitude.

• Korean Journal of Optics and Photonics
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• v.18 no.2
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• pp.162-166
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• 2007

In this paper, we propose a WDM optical true time-delay (OTTD) beam former for phased way antenna (PAA) systems. It is composed of a delay lines matrix and a multiwavelength source with discrete DFB laser diodes. The building block of a delay lines matrix is a $2\times2$ optical MEMS switch with proper fiber-optic delay line connected between cross ports. A $4\times3$ matrix using four DFB lasers has been fabricated with unit time-delay difference of 12 ps. Maximum time-delay error was measured to be -1.74 ps and +1.14 ps at a radiation angle of $46.05^{\circ}$, corresponding to error range of $-2.87^{\circ}\sim+1.88^{\circ}$. By measuring time-delays at six different RF frequencies from 5- to 10-GHz, we verified the true time-delay characteristic of our OTTD.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.4
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• pp.683-690
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• 2018

In this paper, a new signal processing technique is proposed for calibrating gain, phase, delay offsets in array antenna based anti-jamming minimum variance distortionless response (MVDR) global-positioning-system (GPS) receivers. The proposed technique estimates gain, phase and delay offsets across the antennas, and compensates for the offsets based on the estimates. A pilot signal with good correlation characteristics is used for accurate estimation of the gain, phase and delay offsets. Based on the cross-correlation, the delay offset is first estimated and then gain/phase offsets are estimated. For fine delay offset estimation and compensation, an interpolation technique is used, and specifically, the discrete Fourier transform (DFT) is employed for the interpolation technique to reduce the computational complexity. The proposed technique is verified through computer simulation using MATLAB. According to the simulation results, the proposed technique can reduce the gain, phaes and delay offset to 0.01 dB, 0.05 degree, and 0.5 ns, respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.632-636
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• 2006

It is needed to use the beam scanning to control the cell coverage of the base station considering operation conditions, season, time period, radiation character and mobility of customers and vehicles for varied wireless communication service and quality improvement. This paper proposes a mobile antenna system which can obtain the characteristics of the beam scanning by controlling the directivity depending on the operation condition. Radiation block is made of 2 sub-array of $1\times3$ patched antennas for ITS of 5.8GHZ bandwidth with the gain of 13dBi, and of 2 sub-array of single patched antenna for WiBro of 2.3GHZ bandwidth with the gain of 12dBi. RF module is made of a switch, an amplifier, a PAD, a 3-Bit phase shifter, and a power divider. The system is able to control the beam tilting with electronic methode by using 3-bit phase shifter$(45^{\circ},\;90^{\circ},\;180^{\circ})$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.2
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• pp.169-172
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• 2019

Frequency-modulated continuous wave(FMCW) radars with array antennas are widely used because of their light weight and relatively high resolution. A usual approach for the joint range and angle estimation of a target using an array FMCW radar is to create a range-angle matrix with the deramped received signal, and subsequently apply two-dimensional(2D) frequency estimation methods such as 2D fast Fourier transform on the range-angle matrix. However, such frequency estimation approaches cause bias errors since the frequencies in the range-angle matrix are not independent. Therefore, we propose a new maximum likelihood-based algorithm for joint range and angle estimation of targets using array FMCW radar, and demonstrate that the proposed algorithm achieves the Cram?r-Rao bounds, both for range as well as angle estimation.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.3
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• pp.407-416
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• 2021

An active phased array antennas can not only electrically steer the beam by controlling the weighting of the excitation signal, but can also form a pattern null in the direction of the interference source. The weight of the excitation signal to steer the main beam can be easily calculated based on the position of the radiating element. In addition, the weight of the excited signal for pattern null formation can also be calculated by setting the required radiation pattern and using WLSM(Weighted Least Squares Method). However, in a general wireless communication network environment, the location of the interference source is unknown. Therefore, an adaptive pattern null synthesis is needed. In this paper, it was confirmed that pattern null synthesis according to the required radiation characteristic was possible. And based on this, adaptive pattern null synthesis into the direction of an interference source was studied using a binary search algorithm based on observation area. As a result of conducting a simulation based on the presented technique, it was confirmed that adaptive pattern null forming into the direction of an interference is possible in efficient way.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.6
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• pp.1033-1038
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• 2022

In this paper, the design of a printed dipole antenna fed by broadside coupled striplines (BCS) for the 3.5GHz band is described. The two fins of the bow tie are, respectively, on the two sides of the substrate. The feeding balanced lines adopted for 1×2 array are the BCS. The obtained numerical results are in good agreement with experimental data. Through experiments with printed dipole antennas of various extended angles, the printed dipole antenna exhibits the wide bandwidth in the desired frequency band, which has a bandwidth of 28% for VSWR < 2.0 : 1. And within this bandwidth, This printed dipole antenna achieves a stable radiation pattern. It is found that the narrow band and feeding for array characteristic which is a disadvantage of the conventional printed dipole antenna can be improved. The radiation pattern showed omnidirectional characteristics and the maximum gain was about 4.4dBi.

• Journal of Advanced Navigation Technology
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• v.27 no.4
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• pp.463-468
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• 2023

In this paper, we proposed reconfigurable dual polarization patch array antenna that can select two polarizations(Vertical, RHCP) using defected ground structure and Pin diode. The proposed antenna was designed arranging a circular polarization patch antenna implemented with a square microstrip patch and two slots 3x3 at 25.8mm placed, a half-wavelength of 5.8 GHz. Conect the pin diode and the capacitor to the slot diagonally placed on the ground of each antennas, and select polarization using the open/short operating according to the application of DC voltage to the pin diode. As a result of the design, the gain of the antenna is 11.7 dBi at vertical polarization and 11.6 dBic at RHCP. The axial ratio is 20.3 dB at 1.8 dB vertical polarization at RHCP. Mutual Coupling is Maximum to -20.8 dB for vertical polarization and Maximum to -30.1 dB for RHCP.