광대역 동축선로 임피던스 변환회로의 동작 특성 분석

박웅희,Park, Ung-hee 한국정보통신학회 2019 한국정보통신학회논문지 Vol.23 No.2

Using two or more coaxial lines, if one port is connected in series and the other port is connected in parallel, it can be implemented the wideband transmission line transformer(TLT). Because the wideband TLT utilizes the outer conductor of the coaxial line, it is difficult to predict the characteristics. In this paper, based on the analysis for the transfer characteristic(S21) according to the loss of the each line in ${\lambda}/4$-microstrip line TLT, the operating characteristic of the fabricated wideband 4:1 TLT using two $25{\Omega}$-coaxial lines is investigated. The fabricated wideband TLT shows the notch characteristic in which the transfer signal sharply decreases at ${\lambda}/4$ frequency of the coaxial line and has a value within -0.2dB of the transfer characteristic(S21) in $0.06{\sim}0.2{\lambda}$ frequency range of the coaxial line. This transfer characteristics(S21) can change the operating frequency range slightly and set the optimum transfer characteristic(S21) at the desired frequency by changing the length of the microstrip line.

링-하이브리드 커플러를 이용한 가변 전력 분배기 회로

박웅희,Park, Ung-hee 한국정보통신학회 2016 한국정보통신학회논문지 Vol.20 No.2

This paper introduces a new variable power divider circuit with an arbitrary power division ratio ranging from $1:{\infty}$ to ${\infty}:1$. The proposed power divider circuit consists of one branch-line coupler to be a good input matching characteristic, two variable phase shifters with 90-degree phase variation to be connected two output paths of the branch-line coupler, and one ring-hybrid coupler to combine output signals of two variable phase shifter. The power division ratio between the two output ports of the proposed power divider can be easily controlled by the phase variation of the two phase shifter. The proposed power divider circuit fabricates on laminated RF-35 (h = 20 mil, er=3.5; Taconic) with a center frequency of 2 GHz. The power division ratio of the fabricated prototype varies from about 1:1000 to 5000000:1, with an input reflection characteristic(S11) of below -20 dB, an insertion loss of about -1.0 dB, and an isolation characteristic of below -17 dB between two output ports in the range 1.9-2.1 GHz.

동축선을 이용한 광대역 전력 분배기

박웅희,Park, Ung-Hee 한국정보통신학회 2012 한국정보통신학회논문지 Vol.16 No.4

A coaxial-cable impedance transformer that can be used in high power and wideband frequency range is an arbitrary impedance transformation ratio by an additional coaxial cable. The coaxial-cable impedance transformer to be 50-${\Omega}$ to 25-${\Omega}$ impedance transformation ratio is easily operated an wideband power divider by connecting two 50-${\Omega}$ lines at 25-${\Omega}$ impedance point. This wideband power divider has a poor output matching characteristic and a poor isolation characteristic between two output ports. In this paper, it proposes a coaxial-cable power divider to be a good output matching and isolation characteristics as it uses the singly terminated filter design theory. The odd-mode operation characteristic of the suggested power divider to use singly terminated low pass filter coefficient due to matching order and ripple value is examined by ADS program. And, it fabricates and measures the operation characteristic of 2-way power divider with 2nd-order and 4th-order matching circuit.

이중 특성 임피던스 선로를 이용한 Gysel 3:1 가변 전력분배기

박웅희,Park, Ung-hee 한국정보통신학회 2021 한국정보통신학회논문지 Vol.25 No.10

The Gysel divider has the advantage of easily setting the resistor in the circuit. If the line impedance in the Gysel divider is set differently, the input signal can be distributed to the two output ports at various distribution ratios. This paper proposes the Gysel divider that can change the power distribution to 1:3 or 3:1 by changing the line impedance. The impedance change of the line can be implemented by placing a floating copper plate on the bottom of the microstrip-line. When the floating copper plate and the ground plane are connected, the line operates as the microstrip-line, and when the floating copper plate and the ground plane are disconnected, the line operates as the coplanar-line. The proposed Gysel divider was fabricated at the center frequency of 1.5GHz. The fabricated 3:1 Gysel divider has a stable value S₁₁ of below -17dB, S₂₁/S₃₁ of 4.8±0.2dB, S₂₁(to high output port) of -1.39±0.12dB and S₃₁(to low output port) of -6.15±0.08dB over 1.3~1.7GHz.

위성을 이용한 인터넷 통신용 이동 안테나의 수신시스템 설계 및 제작

박웅희,손성호,노행숙,이경희,전순익,Park Ung Hee,Son Seong Ho,Noh Haeng Sook,Lee Kyoung Hee,Jeon Soon Ik 대한전자공학회 2004 전자공학회논문지TC (Telecommunications) Vol.41 No.12

The land mobile antenna for two-way communication using geostationary satellite consists of a transmitting and receiving systems. The transmitting system plays the role of sending the signal to the satellite while the receiving system does the role of receiving signal from the satellite and tacking the target satellite. Especially, the land mobile antenna for satellite communication must be met with the international regulation such as antenna pattern, transmitting power and tracking error to protect the damage of the neighbor satellites. On the other hand, this paper thoroughly examined a receiving system to satisfy a stable satellite tracking performance and antenna pattern specified by the international regulation for Ku-band geostationary satellite.

초고주파 전력 트랜지스터의 Sweet spot에서의 위상 변화 특성 연구

박웅희,장익수,조한유,Park, Ung-Hee,Chang, Ik-Soo,Cho, Han-You 대한전자공학회 2001 전자공학회논문지TC (Telecommunications) Vol.38 No.1

When the high power transistor is used for amplifier in microwave frequency, the bias of transistor is usually AB-class or B-c1ass because of power efficiency. The sweet spot point having small IMD signal compared with near neighborhood exicts frequently in the high power transistor using AB class bias or B-class bias. On the sweet spot, the magnitude and phase of the main and IMD signal of HPA output change as the input signal power change, respective the relative phase on the sweet spot changes rapidly. If we know exactly the magnitude and phase characteristics of IMD signal, we can design a more adequate linearizer and understand the characteristics of transistor. In this paper the magnitude and phase of the main and IMD signal of HPA output on the sweet spot are measured using the designed hardware.

브랜치라인 커플러 결합을 이용한 가변 전력 분배기 회로

박웅희,Park, Ung-hee 한국정보통신학회 2017 한국정보통신학회논문지 Vol.21 No.2

The proposed variable pawer divider in this paper is composed of one equal power 2-way Wilkinson power divider, two variable phase shifters with 90-degree phase variation to be connected two output paths of the 2-way power divider, and one branchline coupler to combine output signals of two variable phase shifter. The proposed variable power divider can theoretically have an arbitrary power division ratio ranging from ${\infty}:1$ to ${\infty}:1$ due to 90-degrees phase variation of two phase shifter. The proposed power divider circuit fabricates on laminated TLX-9(h=20 mil, er=2.5; Taconic) with a center frequency of 1.7 GHz. The power division ratio of the fabricated prototype varies from about 1:100 to 200:1, with an input reflection characteristic(S11) of below -16 dB, an insertion loss of about -1.0 dB, and an isolation characteristic of below -17 dB between two output ports in the range 1.65-1.75 GHz.

저손실 광대역 동작 특성을 가지는 동축 선로 임피던스 변환기 제작

박웅희,Park, Ung-hee 한국정보통신학회 2017 한국정보통신학회논문지 Vol.21 No.12

The coaxial line impedance transformer that performs impedance conversion using the coupling of two or more coaxial lines of the same length is often used for impedance matching in the low frequency region due to many advantages. This paper measures the phase and magnitude characteristics of each coaxial line in a 4:1 coaxial line impedance transformer using two 100mm coaxial lines. This experiment shows that it is more effective to make the length of the auxiliary coaxial line shorter than the main coaxial line by about 5 mm in order to realize a low loss impedance transformer. In addition, it measures the transmission characteristics by directly connecting a 4:1 impedance transformer and a 1:4 impedance transformer. This experiment shows that it is effective to connect a 1pF capacitor between the ground and the outer conductor input point of the main coaxial line in order to increase the operating frequency range.

월킨슨 분배기와 90도 위상차 분배기를 이용한 RF 마이크로스트립 발룬

박웅희,임종식,김종면,Park Ung-Hee,Lim Jong-Sik,Kim Joung-Myoun 한국전자파학회 2005 한국전자파학회논문지 Vol.16 No.3

A RF microstrip balun having low transmission loss for the balanced receiving dipole antenna is designed and fabricated using a three-section Wilkinson divider and two 3-dB quadrature couplers. It considers two types of the three-section Wilkinson dividers, the Cohn's optimum three-section structure and the miniaturized three-section structure, for wideband power splitting. Also, two 3-dB quadrature couplers for 180 degrees of phase difference adopt a twist-wire coaxial cable. The fabricated first balun having the Cohn's optimum three-section Wilkinson divider has 0.5 dB of transmission loss, $\pm$0.2 dB of amplitude imbalance, and 180$\pm$2.3 degrees of phase imbalance over 400 to 1000 MHz by measurement. The second one using the miniaturized three-section Wilkinson divider shows 1.0 dB of transmission loss, $\pm$0.7 dB of amplitude imbalance, and 180$\pm$8.8 degrees of phase imbalance over the same frequency band.

위성통신을 위한 송수신 겸용 삼중 적층 마이크로스트립 패치 배열 안테나 설계

박웅희,노행숙,Park, Ung-Hee,Noh, Haeng-Sook 한국정보통신학회 2007 한국정보통신학회논문지 Vol.11 No.5

본 논문은 Ku-대역 위성 통신에서 배열 안테나의 하나의 단일 안테나로 사용 가능한 송/수신 겸용 구조의 마이크로스트립 패치 배열 안테나에 관한 것이다. 본 논문에 제시된 마이크로스트립 패치 배열 안테나의 단일소자인 하나의 마이크로스트립 패치 안테나는 고이득과 광대역 특성을 구현하기 위하여 한 개의 방사패치와 두 개의 기생패치로 구성된 삼중 적층 구조 형태로 설계하였다. 이러한 단일 패치 안테나 소자는 고이득의 특성을 얻기 위하여 $1{\times}8$ 배열 구조로 배열하였으며, 안테나 크기 및 급전 손실을 고려하여 직렬과 병렬 급전을 혼합하여 급전 회로를 설계하였다. 제안된 삼중 적층 송/수신 겸용 배열 안테나는 무궁화 3호 위성과의 방송 및 통신 송수신을 위해 송신 주파수대역($14.0{\sim}14.5GHz$)은 수직편파, 수신 주파수대역($11.1{\sim}12.75GHz$)은 수평편파로 설계하였다. 설계한 안테나의 타당성을 검증하기 위하여 삼중 적층 구조의 마이크로스트립 패치 안테나를 실제 제작 및 측정하였다. 그 결과 송/수신 대역 내에서 배열 안테나 이득은 $17{\sim}18dBi$이고, 임피던스 대역폭은 전대역에서 10% 이상의 결과를 보이며, 교차편파 레벨은 -25 dB 이하, 부엽레벨은 -9.4 dB 이하의 양호한 결과를 보였다. This paper presents a microstrip patch array antenna having transmission feed and reception feed for satellite communication in the Ku band. In this paper, the element of the patch array antenna is a three-stacked structure consisting of one radiation patch and two parasitic patches for high gain and wide bandwidth characteristics. To obtain higher gain, the unit elements are expanded into a $1{\times}8$ may using a mixture of series and parallel feeds. The proposed antenna has horizontal polarization for the Rx band and vertical polarization for the Tx band. To verify the practicality of this antenna, we fabricated a three-stacked patch array antenna and measured its performance. The gain of the array antenna in the Rx and Tx bands exceeds 17 and 18 dBi, respectively. The impedance bandwidth is over 10 % in both bands. The cross-polarization level is below -25 dB, and the sidelobe level is below -9.4 dB.