• ETRI Journal
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• 제36권2호
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• pp.309-312
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• 2014

A novel compact pattern diversity slot antenna for ultra-wideband (UWB) and Bluetooth applications is presented. This antenna consists of two modified coplanar waveguides that feed staircase-shaped radiating elements, wherein two different fork-like stubs are placed at the $45{\circ}$ axis. The measured results show that this proposed antenna operates from 2.3 GHz to 12.5 GHz, covering Bluetooth, WLAN, WiMAX, and UWB. The performance of radiation patterns and the corresponding envelope correlation coefficient prove this antenna is suitable for MIMO/diversity systems. Also, the antenna's compact size makes it a good candidate for portable devices.

• 전자공학회논문지
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• 제50권2호
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• pp.54-59
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• 2013

이중대역에서 동작하는 브랜치 라인 커플러를 나타낸다. 새로운 설계 구조에서는 단락 스터브가 병렬로 추가된 전송선로가 2개의 주파수에서 $90^{\circ}$의 위상 천이를 구현하기 위하여 사용된다. 제안하는 브랜치 라인의 특성 임피던스와 전기적 길이는 종래의 구조와 비교하여 조정된다. ABCD 행렬 파라미터를 이용하여 설계 방정식을 유도하였다. 설계 개념을 검증하기 위하여 0.8 GHz 및 1.85 GHz에서 동작하는 마이크로스트립 커플러를 제작하고 측정하였다.

• 전자공학회논문지A
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• 제29A권2호
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• pp.18-23
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• 1992

Recently, SSPAs(Solid-State Power Amplifiers) with high linearity and efficiency replace TWTAs (Traveling-Wave-Tube Amplifiers) in satellite transponders. In this paper, a power amplifier with maximum output power is designed and constructed using GaAs FET(MGF-1302) as a test model for the development of SSPAs. For conjugate matching of input and output network, transimission lines and stubs are optimized using microwave CAD program, LINMIC+. Power amplifier is realized on the teflon substrate($\in$S1rT=2.45) with a bandwidth of 1GHz at a center frequency of 8GHz. Maximum stable gain of simulation and simulation and experimental result is obtained 9.23, 7.65 dB, respectively.

• ETRI Journal
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• 제34권4호
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• pp.536-541
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• 2012

This paper aims to extend the transmission line matrix method with a hybrid symmetrical condensed node (HSCN) to model ferrite media in the time domain. To take into account the anisotropy and dispersive properties of ferrite media, equivalent current sources are incorporated into supplementary stubs of the original HSCN. The scattering matrix of the proposed HSCN is provided, and the validity of this approach is demonstrated for both transversely and longitudinally magnetized ferrites. Agreement is achieved between the results of this approach and those of the theoretical and the finite-difference time-domain method.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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• pp.273-277
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• 2003

This paper presents a structure of the Wilkinson power divider that can suppress the 9ea harmonic output. The power divider consists of ${\lambda}/4n$ open stubs, which are located at the $3{\lambda}/4$ branches and parallel connection of resistor which shunts the output ports. Experimental results show that this power divider suppresses from 1st to 9th harmonic components to less than -37dB, while maintaining the characteristics of a conventional Wilkinson power divider; featuring an equal power split, a simultaneous impedance matching at all ports and a good isolation between output ports. these results agree quite well with the simulation results.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2006년도 하계학술대회
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• pp.175-178
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• 2006

We present a ring hybrid balun with additional two ${\lambda}/4$ short stubs that offers excellent amplitude and phase balance performance. The phase difference which is essentially occurred in $180^{\circ}$ ring hybrid is compensated by a ${\lambda}/4$ short stub in one output port. To compensate the amplitude imbalance inherent in the ring hybrid, the series resistance will be added to the second stub which is connected to another output port. The measured balun shows that phase imbalance is less than $2.5^{\circ}$ and magnitude imbalance is less than 0.2dB over a 1.75-2.25 GHz.

• 대한전자공학회논문지TC
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• 제47권6호
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• pp.22-25
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• 2010

이 논문은 브랜치라인 커플러에서 고조파 신호를 제거할 수 있는 변형된 설계 방법을 제안한다. 기존의 1/4 파장 길의의 전송선로의 중앙에 개방형 스터브를 추가한 후에, 설계 주파수에서는 커플러의 기능을 제공하고 고조파 주파수에서는 전송을 제한하는 특성을 갖는 커플러의 해를 구하는 것이 가능하다. 이의 검증 예로서 1.0GHz에서 커플러를 제작하였으며 2.0GHz와 3.0GHz에서 -37.5dB 및 -42.7dB의 억압비를 나타내었다.

• Journal of electromagnetic engineering and science
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• 제1권1호
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• pp.43-47
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• 2001

A compact size microstrip antenna element using FR-4 substrate is proposed for use in repeater and base stations. Two stacked patches are aperture-coupled by two split feedlines. Rectangular stubs on the split feedlines are laid under the aperture and have the effect of considerably lowing the magnitude of $S_{11}$ [dB] and broadening impedance bandwidth. The designed structure has been fabricated and measured. Based on 20 dB, the return loss bandwidth is about 16.8% (1.86 GHz~2.20 GHz), which covers the frequency range assigned for IMT-2000 with a large margin. The overall dimension of the proposed antenna structure is 37 mm$\times$41 mm$\times$19mm (very compact). The antenna gain is more than 7.5 dBi over the required frequency range.

• Journal of electromagnetic engineering and science
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• 제11권3호
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• pp.186-191
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• 2011

This paper presents a simple and effective method for improving stopband rejection characteristics of previously studied dual-band filters. Small electric couplings were applied to the symmetrically positioned shunt resonators, which divided each transmission zero into two transmission zeros without any effect on passbands. We were able to achieve improved stopband rejection characteristics by these additional transmission zeros. For the filter application, we designed a dual-band filter with improved stopband characteristics using microstrip quasi-lumped elements. The electric couplings that control the location of transmission zeros are controlled by the distance between symmetric open stubs of the filter. The filter was fabricated with a relative dielectric constant of 3.5 and a thickness of 0.76 mm. The fabricated filter has a small size ($14.6{\times}13.2{\times}0.76$ mm) and a low insertion loss when compared with conventional filters.

• 한국통신학회:학술대회논문집
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• 한국통신학회 1984년도 추계학술발표회논문집
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• pp.19-21
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• 1984

A design of digital loaded-line phase shifter circuits with PIN Diode is presented. A computer program showes that any phase difference which is satisfied with the condition of minimun VSWR can be obtained with variable stub length and spacing between stubs. A 30 phase bit is designed and measured at 3Gh. Experimental and theoretical performance are compared and found to be in good agreement.