• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.10
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• pp.1807-1813
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• 2007

This paper deals with extending the variable natural oscillation frequency range of an active integrated FET oscillator. In this paper, we conform experimentally that the variable range of the natural oscillation frequency is expanded about three times in the oscillator controlled by the varactor diode. When the frequency difference is given to the oscillators in the two element antenna system, phase difference appeared between the oscillators. The 2-, 3-, 4-, 5-element patch antenna arrays are composed for the beam scanning experiments. All the above patch antennas show good phased array characteristics. The range of the scanning angle is about $30^{\circ}$, and the radiation power is gradually increased from $50{\mu}W\;to\;200{\mu}W$. The radiation patterns we sharpened as the number of elements is increased.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.3 s.118
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• pp.315-322
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• 2007

In this paper, active integrated antenna with left hand circular polarization(LHCP) for a transmitter of UHF RFID reader has been described. A novel rectangular ring patch as a radiator of the active antenna is proposed for easier impedance matching, smaller patch size, and LHCP characteristics. An amplification circuit is placed in the opening area of the radiator and is combined with it to work as oscillating circuit around 915 MHz. From the test results, impedance bandwidth of 29 MHz, 3 dB axial ratio bandwidth of 20 MHz, 3 dB beamwidth of 85 degree, and effective radiation power of 8.8 dBm have been obtained.

• Journal of Satellite, Information and Communications
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• v.1 no.1
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• pp.54-58
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• 2006

A new design for easily controlling operating frequency of an antenna-integrated planar oscillator is introduced. The oscillator circuit of a broadband negative-resistance active part and a passive load including a patch antenna. The patch resonance is used for determining the oscillation frequency. This design reduces the possibility of mismatch between antenna radiation and oscillation frequencies. To achieve optimum output power, load-pull simulation for the negative-resistance circuit is used. The load-pull simulation shows the feed point and the delay of feed line can affect the oscillation power. Two negative-resistance circuits capable of supporting oscillation over full C-band and X-band are fabricated. The oscillation frequency, output power and phase noise for different patch antennas are measured.

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.1 s.24
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• pp.33-40
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• 2006

A compact broadband active composite dipole antenna for direction finding system at the V/UHF-band is presented. It uses the composite structure which improves the antenna gain and the active circuit for broadband operation. This type of antenna has a high gain more than that of one dipole antenna within limited length(1m). The basic design and performance of both antenna structure and integrated active circuit are presented.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.28-31
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• 2004

This paper describe analysis active microstrip antenna with low noise amplifier at 900 MHz for mobile communication. The microstrip patch antenna is integrated with low noise amplifier on a permittivity 4.5 (Epoxy-FR4) and thickness of substrate 1.6 mm. Low noise amplifier is designed by using GaAs FETs. The analysis characteristics of antenna include return loss, input impedance, vswr, radiation pattarn, bandwidth and gain of antenna. Mesurement gain of antenna is shown 19.2435 dBi.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.11B
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• pp.1612-1619
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• 2001

This paper examines the design, implementation characteristics of a folded dipole active integrated antenna. Our goal was to minimize the physical size of RF circuit and its insertion loss, and to make the high frequency tuning easier by directly integrating the ISM(Industrial Scientific & Medical) band power amplifier and antenna. Non-linear model has been used for highly accurate simulation of the power amplifier. The maximum power level was found by using the Load pull method before an impedance matching was achieved. It is found that the total power-added efficiency(PAE) including the driving amplifier was 31.5% and that the transmit power was 13.7 dBm. We also found that the proposed scheme with the smaller antenna as compared with the existing dipole antenna has 23.7 dB total gain including the antenna gain. The suppression of the second harmonic signal to the fundamental signal with respect to the fundamental signal was found to be more than 30 dBc.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.9
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• pp.1098-1106
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• 2007

This paper presents active antenna diplexers implemented into an ultra-wideband CPW(Coplanar Waveguide) fed monopole antennas. The proposed active antenna diplexer is designed to direct interconnect the output port of a wideband antenna to the input port of two active(HEMT) devices, where the impedance matching conditions of the proposed active integrated antenna are optimized by adjusting CPW(Coplanar Waveguide) feed line to be the length of 1/20 $\lambda_0$(@5.8 GHz) in planar type wideband antenna. The measured bandwidth of the active integrated antenna shows the range from 2.0 GHz to 3.1 GHz and from 5.25 GHz to 5.9 GHz. The measured peak gains are 17.0 dB at 2.4 GHz and 15.0 dB at 5.5 GHz.

• Journal of electromagnetic engineering and science
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• v.2 no.2
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• pp.112-116
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• 2002

In this paper, the active integrated antenna(AIA) using a wideband printed dipole antenna and a balanced amplifier is designed and fabricated. The proposed active printed dipole antenna has characteristics of easy matching, wide bandwidth and higher output power To feed balanced signal to printed dipole, a Wilkinson power divider and delay lines are used. The measured result shows that, at 6 GHz center frequency, the impedance bandwidth is 22 % (VSWR < 2), 3 dB gain bandwidth is 28 %, the maximum gain is 14.77 dBi, and output power at P1 dB point is 23 dBm.

• The Journal of the Korea institute of electronic communication sciences
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• v.4 no.2
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• pp.87-92
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• 2009

In this paper, we designed and fabricated the active amplification block for the integrated antenna module. The fabricated amplification module have a proper gain and low noise figure in the band of AM/FM band, T-DMB band and GPS band, and show good isolation performance for each band. Manufactured circuits satisfied the gain performance 7 dB in AM band, 11 dB in FM band, 10 dB in T-DMB, and 17 dB in GPS band. The integrated amplification block was realized by 35 mm*35 mm size, and was shown as the same sensitivity performance as compared with a conventional reference antennas.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.3
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• pp.227-247
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• 2015

An X-band $8{\times}16$ dual-polarized active phased array antenna system has been implemented based on the substrate integrated waveguide(SIW) technology having low propagation loss, complete EM shielding, and high power handling characteristics. Compared with the microstrip case, 1 dB less is the measured insertion loss(0.65 dB) of the 16-way SIW power distribution network and doubled(3 dB improved) is the measured radiation efficiency(73 %) of the SIW sub-array($1{\times}16$) antenna element. These significant improvements of the power division loss and the radiation efficiency using the SIW, save more than 30 % of the total power consumption, in the active phased array antenna systems, through substantial reduction of the maximum output power(P1 dB) of the high power amplifiers. Using the X-band $8{\times}16$ dual-polarized active phased array antenna system fabricated by the SIW technology, the main radiation beam has been steered by 0, 5, 9, and 18 degrees in the accuracy of 2 degree maximum deviation by simply generating the theoretical control vectors. Performing thermal cycle and vacuum tests, we have found that the SIW array antenna system be eligible for the space environment qualification. We expect that the high efficiency SIW array antenna system be very effective for high performance radar systems, massive MIMO for 5G mobile systems, and various millimeter-wave systems(60 GHz WPAN, 77 GHz automotive radars, high speed digital transmission systems).