• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.3
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• pp.59-65
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• 2019

The EMI shielding effectiveness of the shielding layer thickness was analyzed when the metal shielding layer was placed in the near field of the magnetic probe and the noise source. Microstrip lines were used as noise source, and graphite and ferrite were selected as metal shielding materials. The magnetic probe uses the electromagnetic radiation measurement method using the magnetic probe by applying the IEC 61967-6 method. The transmission coefficient between the microstrip line and the magnetic probe was analyzed. The distance between the two was 1 mm for a single shielding layer and 5 mm for a multiple shielding layer. The thickness of the shielding layer was changed to 5 um, 10 um, 30 um, and 50 um. When the frequency was changed from 150 kHz to 1 GHz, a maximum shielding effectiveness (SE) of 44.9 dB was obtained.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.2
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• pp.165-172
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• 2019

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.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.2
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• pp.338-346
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• 2018

In this paper, a monopole antenna applicable to WLAN/WiMAX system is designed and fabricated. The proposed antenna is designed to have three lines and one slit based on microstrip feeding to have triple band characteristics. We optimized the lengths and slits of the three lines to obtain the required characteristics for this paper. The proposed antenna has $32.0mm(W2+W3){\times}47.1mm$ (L3+L4+L5+L8) on a dielectric substrate of $42.5mm(W1){\times}52mm(L1){\times}1.0mm$ size. From the fabrication and measurement results, bandwidths of 158 MHz (813 to 971MHz), 630 MHz (2.10 to 2.73GHz) and 1190 MHz (4.83 to 6.02GHz) were obtained based on the impedance bandwidth. The fabricated antenna also obtained the measured gain and radiation pattern in the required triple band.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.9
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• pp.862-876
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• 1991

In this theses, the procedure for finding the equivalent immittance of an n-line coupled structures is presented in terms of the normal mode parameters of the n-line coupled system. The above generalized equations can be applied to the various Coupled structures including directional couplers, DC blocks, bandpass/band elimination filters, and various other uniformly coupled filters. The design equations are based on a simplified TEM(Quasi TEM) mode. The obtained results and the definition of the scattering parameters for a general coupled line four port with arbitrary terminations are used to present the procedure to determine the optimum physical dimensions matching the given load impedances connected to input, output port. Multiple coupled rnicrostrip two-port with three lines circuit designed shows little discrepancy between the conventional method and this one. Four port with five lines were fabricated on teflon substrate($e$r=2.55) with its thickness h=l.588mm designed at the center frequency, 4 GHz. Their measured results are fairly close to the ones by computation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.7
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• pp.761-770
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• 2008

Impedance or admittance inverter is a conceptual 2-port device frequently used in microwave filter design. In this paper, the equivalent circuit using inverter for general loss less 2-port circuit is presented. Our equivalent circuit can be directly and easily represented with z- or y-parameters compared with the conventional methods. Based on the representation, the derived results for various coupled lines such as parallel coupled line and anti-parallel coupled lines are compared ours. In addition, the results of other workers for improvement of the distortion in frequency response of microstrip coupled line filter are derived using our representation and compared. The proposed equivalent circuit shows the difference with conventional equivalent circuit so the conventional design method can not be applied to parallel coupled line filter with our representation. So in this paper the novel design method is proposed and we showed the method yields more accurate design results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.12
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• pp.1402-1407
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• 2007

This paper presents a new design method of the Ultra-Wide-Band BandPass Filter using the CRLH-TL(Composite Right- and Left-Handed Transmission-line) having the Metamaterials' properties. Instead of the periodic type or many cells of the CRLH-TL, only the unit cell is used to miniaturize the target component, which can not be realized by the conventional quarter guided-wavelength resonator-based filters. Particularly, the strong coupling essential to the Ultra Wide Band is enabled by the interdigital coupled lines between the grounded stubs. The proposed design scheme is validated by the electromagnetic simulation and measurement of the fabricated filter which shows the total size of 'the guided-wavelength/9.4', the 100 % fractional bandwidth for the UWB, the insertion loss of less than 1 dB and the flat group-delay.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.1
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• pp.1-9
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• 2014

In this paper, a reconfigurable polarization patch antenna that uses a Y-shaped feed is proposed. The proposed antenna consists of a square patch, a Y-shaped feeding structure, a PIN diode, and a bias circuit for diode operation. The structural symmetry/asymmetry of the feeding structure is determined by the on/off operation of the PIN diode that inserted into the side of one of the lines of the Y-shaped feeding structure. For the proposed reconfigurable antenna, the two microstrip lines of the feeding structure have the same length when the PIN diode operates in the on state, and the antenna exhibits linear polarization(LP). On the other hand, when the PIN diode operates in the off state, the length of one side line of the feeding structure is relatively shorter than that of the other line. Therefore, the antenna exhibits circular polarization(CP). From the measurement results, it is found that the proposed antenna exhibits good impedance matching and axial ratio. In addition, polarization switching can be easily achieved in the same operating band.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.4 s.346
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• pp.44-51
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• 2006

In this paper, the resonance characteristics of zigzag wire dipole antennas are first analyzed by the method of moment(MOM) for shortening the space occupation length of straight wire dipole antenna Considering the shortening effect the integrated zigzag dipole antennas with the simplified microstrip feed are designed. Since the integration gives rise to discontinuities due to antenna line width with abrupt bend angles, the compensation by the chamfer is applied. Futhermore the integrated parasitic zigzag lines are properly attached to both sides of substrate for compensation of the effect of the dielectric substrate, hence improving the resonance characteristic. The design results at UHF and ISM band are verified with experiments.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.9 s.112
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• pp.845-851
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• 2006

Folded lines are applied to design a compact microstrip ring hybrid. Using the proposed structure we achieve both significant size reduction and good harmonic suppression with the same results of conventional ring hybrid at 2.41 GHz. Including the third harmonic frequency, up to 11 GHz band harmonics are suppressed to -20 dB. The size of the proposed ring-hybrid is reduced to one forth of the conventional ring hybrid. The measured frequency responses agree well with simulated ones.

• Journal of electromagnetic engineering and science
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• v.4 no.3
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• pp.113-118
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• 2004

As an application of ring filters, a new and simple method to determine an inherent-ring-resonance frequency is introduced. The ring filter consists of a ring and two short stubs. They are connected at 90$^{\circ}$ and 270$^{\circ}$ points of the ring and the ring filter may be seen in such way that two filters are connected in parallel. Therefore, if the two powers of the two filters are out-of-phase at the output, the power excited at the input can not be delivered. That can be done by making difference in length of the two short stubs, and when a certain condition is satisfied, a frequency exists where all the excited power is reflected. That is the very inherent-ring-resonance frequency. In the lossless case, the return loss with the condition reaches 0 dB at the inherent-ring-resonance frequency but does not with conductor, dielectric losses and so on. Therefore, the effective loss tangent at a frequency of interest may be obtained correctly. To verify the method, two ring filters have been fabricated in microstrip lines and the measured results show good agreement with the predicted ones.