• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.8
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• pp.862-877
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• 2008

In this paper, two types of wideband 3-dB ring hybrids are compared and discussed to show the ring hybrid with a set of coupled-line sections better. However, the better one still has a realization problem that perfect matching can be achieved only with -3 dB coupling power. To solve the problem, a set of coupled-line sections with two shorts is synthesized using one- and two-port equivalent circuits and design equations are derived to have perfect matching, regardless of the coupling power. Based on the design equations, a modified ${\Pi}-type$ of transmission-line equivalent circuit is newly suggested. It consists of coupled-line sections with two shorts and two open stubs and can be used to reduce a transmission-line section, especially when its electrical length is greater than ${\pi}$. Therefore, the $3\;{\lambda}/4$ transmission-line section of a conventional ring hybrid can be reduced to less than ${\pi}/2$. To verify the modified ${\Pi}-type$ of transmission- line equivalent circuit, two kinds of simulations are carried out; one is fixing the electrical length of the coupled-line sections and the other fixing its coupling coefficient. The simulation results show that the bandwidths of resulting small transmission lines are strongly dependent on the coupling power. Using modified and conventional ${\Pi}-types$ of transmission-line equivalent circuits, a small ring hybrid is built and named a compact wideband coupled-line ring hybrid, due to the fact that a set of coupled-line sections is included. One of compact ring hybrids is compared with a conventional ring hybrid and the compared results demonstrate that the bandwidth of a proposed compact ring hybrid is much wider, in spite of being more than three times smaller in size. To test the compact ring hybrids, a microstrip compact ring hybrid, whose total transmission-line length is $220^{\circ}$, is fabricated and measured. The measured power divisions($S_{21}$, $S_{41}$, $S_{23}$ and $S_{43}$) are -2.78 dB, -3.34 dB, -2.8 dB and -3.2 dB, respectively at a design center frequency of 2 GHz, matching and isolation less than -20 dB in more than 20 % fractional bandwidth.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.74.3-74
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• 2002

. A Coupled-Field Analysis of Galloping for Power Transmission Line . Fluid-Structure interaction, Galloping, Power Transmission Line, ANSYS

• ETRI Journal
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• v.30 no.5
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• pp.723-728
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• 2008

In this paper, a simple transmission line model for an edge-coupled patch antenna is presented. The coupled section is modeled with a lump network which represents the mutual admittance between patches and from patch to ground. Theoretical analysis of two edge-coupled patch antenna models are compared by simulation and experiment in antennas designed to operate at the 2 GHz band. The proposed model predicts the return loss of the antenna accurately.

• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.2
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• pp.122-129
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• 2001

A characterization procedure for analyzing symmetric coupled MIS(Metal-Insulator-Semiconductor) transmission line is used the same procedure as a general single layer symmetric coupled line with perfect dielectric substrate from the extraction of the characteristic impedance and propagation constant for even- and odd-mode. In this paper, an analysis for a new substrate shielding symmetric coupled MIS structure consisting of grounded crossbar at the interface between Si and SiO2 layer using the Finite- Difference Time-Domain(FDTD) method is presented. In order to reduce the substrate effects on the transmission line characteristics, a shielding structure consisting of grounded crossbar lines over time-domain signal has been examined. Symmetric coupled MIS transmission line parameters for even- and odd-mode are investigated as the functions of frequency, and the extracted distributed frequency- dependent transmission line parameters and corresponding equivalent circuit parameters as well as quality factor for the new MIS crossbar embedded structure are also presented. It is shown that the quality factor of the symmetric coupled transmission line can be improved without significant change in the characteristic impedance and effective dielectric constant.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.11
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• pp.960-965
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• 2015

In this paper, a coupled line directional coupler using an LUC(Low-pass filter Unit Cell) of artificial transmission line is presented. The conventional coupled line coupler is limited in length by the ${\lambda}/4$ transmission line while the proposed coupling structure is implemented smaller than $90^{\circ}$ by inserting the phase delay line between two coupled line, reduced in physical size by configuring a phase delay line with an LUC having the characteristics of a typical transmission line in a particular frequency. A coupler having -10 dB coupling factor at the center frequency of 700 MHz is designed, fabricated. The measured result agrees well with that of conventional one. The length of the fabricated coupled line coupler has about 45 % in length compared to the conventional one.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.283-287
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• 2003

A new method to miniaturize ${\lambda}/4$ transmission line of power divider is proposed. The method utilizes simple combination of the shorted coupled-line pair instead of the transmission line with very high impedance and shunt lumped capacitors. The length of ${\lambda}/4$ transmission line of power divider is about 16% over the conventional power divider at 1 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.114-120
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• 2008

This paper proposed the band pass filter(BPF) with feeding structure using $\pi$-type transmission line by means of transforming the input/output coupled-lines of the half wavelength parallel coupled-line BPF into K-inverter, then substituting $\pi$-type transmission line equivalence for K-inverter. The proposed method supplies solution with what the half wavelength parallel coupled-line BPF's input/output coupled-lines are realized. Also it can quite reduce efforts and time needed to optimize filter performance when is compared to reported method using tapped line structure because formulas is very simple and accurate. On the basic of the proposed method, the BPF with feeding structure using $\pi$-type transmission line has been designed and fabricated. The validity of proposed method was proven by the measured result.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.8
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• pp.61-67
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• 2010

A characterization procedure for analyzing symmetric coupled MIS(Metal-Insulator-Semiconductor) transmission line is used the same procedure as a general single layer symmetric coupled line with perfect dielectric substrate from the extraction of the characteristic impedance and propagation constant for even- and odd-mode. In this paper, an analysis for a new substrate shielding symmetric coupled MIS structure consisting of grounded crossbar at the interface between Si and SiO2 layer using the Finite-Difference Time-Domain (FDTD) method is presented. In order to reduce the substrate effects on the transmission line characteristics, a shielding structure consisting of grounded crossbar lines over time-domain signal has been examined. Symmetric coupled MIS transmission line parameters for even- and odd-mode are investigated as the functions of frequency, and the extracted distributed frequency-dependent transmission line parameters and corresponding equivalent circuit parameters as well as quality factor for the new MIS crossbar embedded structure are also presented. It is shown that the quality factor of the symmetric coupled transmission line can be improved without significant change in the characteristic impedance and effective dielectric constant.

• Journal of Advanced Navigation Technology
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• v.23 no.4
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• pp.309-315
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• 2019

This paper proposes an implementation of unequal power divider with 1:3 and 1:4 splitting ratio in multi-section structure using CPW and offset coupled transmission line. The power divider consists of a multi-section transmission line and a circuit with parallel capacitors and resistors. A multi-section transmission line was implemented by decomposing a ${\lambda}/4$ single transmission line terminated by an arbitrary impedance and converging it with a multi-section transmission line shorter than $90^{\circ}$ electrical length, and RC parallel circuits were connected between transmission lines to obtain reflection coefficient of output port and isolation characteristics between the output port. In this way, it was confirmed that the transmission lines at the unequal power divider designed at 2 GHz were shorter than ${\lambda}/4$ and implemented at least 27% less than the conventional ones, and that the broadband characteristics could be obtained.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.387-390
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• 1998

We propose comb-line filter using SIR(Stepped Impedance Resonator) with two transmission line. The coupling structure of the filter is double coupled line where two coupled lines are linked with cascade. We find out the inverter function of the filter. using even and odd mode impedance. The merits of the filter are that first, we can design transmission zero point at any frequency that we wanted without using lumped elements : chip capacitors and inductors. Second, we can design small size filters. To validate the inverter function of the filter with double coupled line we designed and fabricated two-pole band pass filter with the proposed filter structure.