• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.6
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• pp.636-636
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• 1997

This paper presents the design and fabrication of a shaped-beam array antenna which will be used for a PCS basestation using structure that is coupled to a microstrip line by an aperture on the intervening ground plane. The shaped-beam pattern is obtained by an antenna synthesis method. An array antenna considering the mutual coupling between array elements(patches) and a feeding network are designed by CAD tools. The feeding network is designed by using the Wilkinson power divider to obtain the optimized shaped-beam. The designed results are compared with the measured data.

• ETRI Journal
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• v.37 no.1
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• pp.26-31
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• 2015

Axial-ratio (AR) bandwidth enhancement is achieved for a circularly polarized (CP) cylindrical dielectric resonator antenna (DRA) using a wideband hybrid coupler (WHC) combined with dual probe feed. The presented WHC, comprised of a Wilkinson power divider and a wideband $90^{\circ}$ shifter, delivers good characteristics in terms of 3 dB power splitting and consistent $90^{\circ}$ (${\pm}5^{\circ}$) phase shifting over a wide bandwidth. In turn, the proposed CP DRA, for the employment of the WHC, in place of conventional designs, provides a significant enhancement on AR bandwidth and impedance matching. The antenna prototype with the WHC exhibits a 3 dB AR bandwidth of 48.66%, an impedance bandwidth of 52.5% for voltage standing wave ratio (VSWR) ${\leq}2$, and a bandwidth of 44.66% for a gain of no less than 3 dBi. Experiments demonstrate that the proposed WHC is suitable for broadband CP DRA design.

• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.1063-1066
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• 2000

ln this paper, a new active phase shifter is proposed using a vector sum method, and it is shown that the proposed phase shifter is more efficient than the others in size, power, number of circuits, and gain. Also a unique digital phase control method of the circuit is suggested. The proposed scheme was designed and implemented using a Wilkinson power combiner/divider, a branch line 3dB quadrature hybrid coupler and variable gain amplifiers (VGAs) using dual gate FETs (DGFETs). Furthermore, it is also shown that the proposed scheme is more efficient and works properly with the digital phase control method.

• Journal of electromagnetic engineering and science
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• v.12 no.4
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• pp.280-286
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• 2012

The conventionally classified waves are reclassified in this paper, including the waves associated with metamaterial (MTM) transmission lines. Various types of guided waves in periodic structures are analyzed for 1D Composite Right/Left Handed (CRLH) transmission lines (TL). In addition, dispersion diagrams for 1D CRLH, RH, and LH TLs are presented in terms of radiation conditions. We have refined the design equations of the conventional 1D CRLH TL and proposed a condition to realize the desired phase shift and its slope per unit cell. This condition has been applied to the conventional Wilkinson power divider and realized into MTM added $90^{\circ}$ hybrid coupler. Based on the 10 dB return loss and the $90{\pm}10^{\circ}$ phase shift, the bandwidths of the MTM added $90^{\circ}$ hybrid coupler are 82.25% and 103.5% against the conventional 23% and 52.5%, respectively.

• Proceedings of the KAIS Fall Conference
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• 2009.05a
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• pp.300-302
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• 2009

적층형 가유전체 구조는 유효유전율과 유효투자율은 주어진 표준형 전송선로의 경우보다 증가하므로 결과적으로 전송선로의 길이를 짧게 할 수 있는 장점이 있다. 따라서 회로의 소형화에 유용하게 사용될 수 있는데, 본 논문에서는 한 예로써 대표적인 무선 회로인 윌킨슨 전력분배기의 소형화된 회로에 대하여 기술하고 있다. 표준형 회로와 적층형 가유전체 구조를 이용하여 소형화한 윌킨슨 전력분배기를 2GHz 대역에서 설계하여 실제로 제작하여 측정한 결과를 제시한다. 종래의 표준형 회로와 비교할 때, 동일한 성능을 유지하면서도 회로의 크기가 32%만큼 감소한 결과가 소개된다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.7
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• pp.844-847
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• 2012

By using LHTL(Left-Handed Transmission Line) which is a form of a metamaterial and conventional RHTL (Right-Handed Transmission Line), we designed, fabricated and tested a broadband $90^{\circ}$ coupler which is a basic circuit for I-Q vector signal generation. Synthetic LHTL and RHTL were implemented with capacitors and inductors only, that the size is minimized. Also, by implementing a Wilkinson power divider which is required for the suggested circuit using a synthetic RHTL, the size of whole circuit is only $11mm{\times}12mm$. For the frequency range 0.8~1.25 GHz, the phase difference at the outputs maintained $90^{\circ}{\pm}5^{\circ}$ and thus, a broadband $90^{\circ}$ coupler could be made in a compact form. for the same frequency range, the insertion loss is less than 1.6 dB and return loss is more than 10.1 dB. To the best of our knowledge, this is the smallest and broadband $90^{\circ}$ coupler for the frequency range and if the circuit is made with MMIC(Monolithic Microwave Integrated Circuit) technology, the size will be reduced much further.

• Journal of Advanced Navigation Technology
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• v.21 no.1
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• pp.66-71
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• 2017

This paper describes implementation of a 165 MHz, 5 kW RF high power amplifier (HPA) for particle accelerator applications. The HPA consists of a drive amplifier for main amplifiers driving, sixteen 600 W class-AB push-pull power amplifier pallets and Wilkinson power divider/combiner using lumped LC components, which are divided/combined power amplifier pallet outputs. To detected the amplifier circuit of normal and reflected output power conditions, we used a bidirectional coupler. To radiate heat of main power amplifier, we were used an water-cooled copper plates to go through a water for radiation of heat. The HPA of center frequency 165 MHz has archived an efficiency of 62.5 % at 5 kW of power level experimentally.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.2
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• pp.124-128
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• 2009

This raper proposes a dual-bandstop filter, which is based on a metamaterial transmission line using the composite right/left-handed (CRLH) and dual composite right/left-handed (D-CRLH) structures. The metamaterial structure is used for miniaturization and dual-bandstop operation at the TDMB frequency range (195 MHz) and DVB-T/H frequency range (670 MHz). The size of the proposed filter is $30{\times}15\;mm$, and the -10 dB bandstop fractional bandwidth is approximately 73 % and 50 % at each frequency, respectively.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.5 no.1
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• pp.43-59
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• 2006

A compact and broadband $4\times1$ array antenna was developed for 3G smart antenna system testbed. The $4\times1$ uniform linear away antenna was designed to operate at 1.885 to 2.2GHz with a total bandwidth of 315MHz. The array elements were based on the novel broadband L-probe fed inverted hybrid E-H (LIEH) shaped microstrip patch, which offers 22% size reduction to the conventional rectangular microstrip patch antenna. For steering the antenna beam, a commercial variable attenuator (KAT1D04SA002), a variable phase shifter (KPH350SC00) with four units each, and the corporate 4-ways Wilkinson power divider which was fabricated in-house were integrated to form the beamforming feed network. The developed antenna has an impedance bandwidth of 17.32% $(VSWR\leq1.5)$, 21.78% $(VSWR\leq2)$ with respect to center frequency 2.02GHz and with an achievable gain of 11.9dBi. The design antenna offer a broadband, compact and mobile solution for a 3G smart antenna testbed to fully characterized the IMT-2000 radio specifications and system performances.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.7 no.1
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• pp.41-58
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• 2007

A compact and broadband $4{\times}1$ array antenna was developed for 3G smart antenna system testbed. The $4{\times}1$ uniform linear array antenna was designed to operate at 1.885 to 2.2GHz with a total bandwidth of 315MHz. The array elements were based on the novel broadband L-probe fed inverted hybrid E-H (LIEH) shaped microstrip patch, which offers 22% size reduction to the conventional rectangular microstrip patch antenna. For steering the antenna beam, a commercial variable attenuator (KAT1D04SA002), a variable phase shifter (KPH350SC00) with four units each, and the corporate 4-ways Wilkinson power divider which was fabricated in-house were integrated to form the beamforming feed network. The developed antenna has an impedance bandwidth of 17.32% ($VSWR{\leq}1.5$), 21.78% ($VSWR{\leq}2$) with respect to center frequency 2.02GHz and with an achievable gain of 11.9dBi. The design antenna offer a broadband, compact and mobile solution for a 3G smart antenna testbed to fully characterized the IMT-2000 radio specifications and system performances.