• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.9
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• pp.1949-1956
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• 1997

The mode parameters of asymmetrical coupled microstrip lines on composite substrates are derived by using closed form expression. A 10 dB directional couplers, where the center frquency is 1.8 GHZ, are fabricated on a single-layer substrate and on compsite substrates respectively. It is shown that coupler on a single-layer substrate.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.2
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• pp.286-291
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• 2011

Directional couplers are widely used in RF and microwave applications to distribute or monitor signals. This paper presented a new structure of microstrip branch line directional coupler with coupled lines. The loose couplings of microstrip branch line directional couplers are impractical for the high characteristic impedance values required for the shunt branches. To overcome this limitation, the parallel coupled lines with the shorts were used for the high characteristic impedance. The results of the simulations and measurements were presented for the proposed branch line directional coupler. Measurement of the 10 dB branch line directional coupler shows that the return loss is higher than 30 dB over 10 % bandwidth and the isolation is 35 dB or better over 8 % bandwidth.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.12B
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• pp.1724-1732
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• 2001

In this paper, a technique for increasing the bandwidth of microstrip array antennas using the parallel coupled lines on a single layer is presented. Four types of wideband microstrip array antenna are designed and the characteristics of each type are analyzed. In addition, an iterative method using a distributed network is proposed to design the parallel coupled lines as a wideband impedance matching network. Measurements show that the proposed antennas provide wider bandwidths ∼1.7 times those of conventional microstirp array antennas, while the sizes of proposed antennal are the same as that of a conventional array. And low cross-polarization level can be obtained through symmetrical locations of the parallel coupled lines section

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.6 s.121
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• pp.680-688
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• 2007

Time domain closed-form analytical solutions to the coupled telegrapher's equations for the voltage and current on a lossless multiconductor transmission line are presented. The resulting expressions are obtained in the form of exact time domain propagators operating on the line voltage and current. Time domain numerical methods are developed and examples showing exceptionally accurate results are obtained for uniform and nonuniform; symmetric and asymmetric strip lines.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.328-332
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• 2000

본 논문에서는 기생 패치 구조와 적층 구조의 광대역 마이크로스트립 안테나에 평행 결합 선로 형태의 광대역 임피던스 정합 회로를 결합하여 쉽게 추가적인 임피던스 대역폭 개선을 얻을 수 있음을 제안하였다. 평행 결합 선로 형태의 광대역 임피던스 정합 회로 설계를 위하여 분포 회로 방식의 반복적인 방법을 제시하였고. 설계\ulcorner제작 결과 기생 패치 구조와 적층 구조에서 각각 56.23%와 16.45%의 추가적인 임피던스 대역폭 개선을 이룰 수 있었다. 그리고 방사 패턴과 측정된 이득을 보면 평행 결합 선로의 결합으로 인한 방사 패턴에서의 큰 변화는 보이지 않았고, 이득에서는 평행 결합 선로 부분의 커플링 손실로 인해 최대 이득이 약 1 dB 정도 감소하는 것을 확인할 수 있었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.3
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• pp.553-559
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• 1994

A coupled microstrip-slot line is analyzed using a full wave method in the specral domain. The characteristics of the coupled microstrip-slot line are obtained based on the Galerkin`s method. The characteristics of even mode by microstrip line and odd mode by slot line are calculated respectively. Especially the singularity of basis function is enforced to be considered with respect of modes. Numerical results are compared with available data and shown good agreement.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.63-64
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• 2015

In this paper, a microstrip array antenna capacitively coupled to a microstrip line is studied. The array antenna consists of uniformly spaced rectangular microstrip patches arranged close to a feeding microstrip line on a grounded dielectric substrate. The effects of various parameters, such as strip width and length, distance between adjacent patches, gap between strip patches and microstrip feed line, on the antenna performance were examined. By properly adjusting geometrical parameters, the array suitable for a high gain antenna for use in a frequency band centered at 12.5 GHz was designed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.6
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• pp.598-604
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• 2011

A method of miniaturizing branch line coupler with connected coupled lines is presented. The quarter-wavelength transmission lines in the typical microstrip branch line coupler are replaced with the connected coupled lines with same characteristics of ones for compact size. The connected coupled line is analyzed by T-equivalent circuit and Z parameters based on the even-odd mode analysis. The proposed branch line couplers with connected coupled line are designed and fabricated on FR4 substrate at 2.4 GHz. The measured results show good agreement with theoretical prediction. And the experimental results show that the size of coupler is 37 precent smaller than conventional coupler. This minimized coupler is suitable for Butler Matrix as feeder for mobile communication beam forming antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.5
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• pp.516-524
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• 1997

The propagation properties of various pulse signal types(square pulse, Gaussian pulse, trapezoid pulse, RF pulse) on coupled microstrip lines are investigated. Numerical integration technique which has its accuracy and is easily simulated, is used to obtain the time domain response of pulse signals. Frequency-dependent characteristics of coupled microstrip line is obtained using Jansen's approximate equation. The propagation properties of pulse signal on coupled microstrip lines is analyzed regarding to its geometric structure (relative permittivity ${varepsilon}_r$ substrate height h, strip width w of the microstrip line) and pulse width ${\tau}$ of signal pulse. The simulation results show that space between two lines is very significant parameter in pulse distortion in comparison of any other parameters. The results of this paper are compatible to the trade-off determination of relative permittivity, substrate height, strip width and pulse width of signal pulse when a design of MIC and MMIC is necessary.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.5
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• pp.79-86
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• 2011

In this paper, a S-band coaxial waveguide-based spatial combiner is proposed. The proposed combiner consists of coaxial waveguide, impedance transformer, and finline-to-microstrip transformer. The coaxial waveguide is used as the host of the combining circuits for higher output power and better uniformity by equally distributing the input power to each element. The finline-to-microstrip transformer is designed by using antipodal antenna, and obtained low reflection coefficient by applying the small reflection theorem. The measurement results show the coaxial waveguide combiner has a maximum combining efficiency of 95%.