• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.2 s.117
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• pp.118-125
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• 2007

Harmonic band of bandpass filter(BPF) is suppressed using coupled mushroom structure. Between double positive (DPS) transmission line such as microstrip and double negative(DNG) transmission line such as one dimensional mushroom structure, strong coupling broadly arises in the cross range of dispersion curves of isolated microstrip and mushroom structure because of complex propagation constant in the cross range. Strong coupling inhibits wave propagation, so that this kind of structure can be utilized as bandstop filter(BSF). This BSF utilizes coupled transmission line instead of coupled resonator, resulting in broad bandwidth(>30 %), shan-rejection, and high rejection level. The strong coupling between DPS and DNG transmissionline makes it possible shorten coupling length, resulting in compact size. In this paper, parallel coupled BSF having center frequency of 4 GHz and 3 dB fractional bandwidth of 40 % is designed and utilized to suppressed spurious mode of two bandpass filters.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.9
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• pp.35-43
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• 2002

In this paper, microstrip ring with a narrow gap is characterized and used as a tunable microwave bandgap (MBG) structure. The center frequency of MBG is mainly determined by the mean circumference of the ring and coincides with odd mode resonance frequency of the ring resonator. The stop band formation by the proposed microstip MBG ring is due to the reflection of electromagnetic waves at the narrow gap introduced in the ring, and the reactive component mounted on the gap makes the stop band vary according to its value. The mounting of capacitor (inductor) is observed to decrease (increase) the center frequency of the stop band. The varactor-mounted microstrip MBG ring is expected to be useful in microwave switches and microwave amplifier circuits.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.2
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• pp.115-123
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• 2009

In this paper, we extract the parasitic elements of the transmission line with the defected ground structure(DGS) and the short-circuited comb line section using the Short-Open Calibration(SOC). The scattering matrixes of short, open and the distributed elements in microstrip line are measured by full electro-magnetic(EM) simulator and Vector Network Analyser(VNA). The electro-magnetic effects of the proposed structures are considered by the II and T equivalent circuits with frequency independent elements, and the relations between the measured scattering parameters and the elements in the circuits are shown by performing 2 port network analysis. Moreover, to design the 2.4 GHz bandpass filter with second order butterworth prototype, the proposed methods are applied. As results, the measured $S_{11}$ and $S_{21}$ indicate -20 dB and -1.3 dB at center frequency, and these are shown within 5 % error compare to the predicted results at $0.5{\sim}5\;GHz$.

• Journal of Advanced Navigation Technology
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• v.4 no.1
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• pp.23-35
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• 2000

In this paper, the design for a PCS base station antenna which is using broadband method by a stacked structure has been studied. The sensitive parameters, such as the parasitic elements, the height of air layer between the upper and lower patch, and the variation of feed point, of the microstrip antenna that has stacked structure in a characteristics variation situation are classified and the characteristics has been investigated through the simulations. A designed antenna has following characters. Impedance bandwidth is Z57.5MHz(VSWR${\leq}$2), horizontal beamwidth is $64.1^{\circ}$, and gain is 14.7dBi. Therefore, it is confirmed the characteristics is good. In this paper, through the designing of a stacked microstrip antenna, we has investigated the availability for Korea PCS base station antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.2
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• pp.143-151
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• 2010

In this paper, a novel rectangular patch antenna is proposed to have Zeroth Order Resonance(ZOR) generated based on the Metamaterial Complosite Right- and Left-Handed(CRLH) structure. Making the in-phase electric field over the entire antenna other than a half-wavelength as the fundamental resonance mode of a standard microstrip patch or its positive multiple, the metallic patch is suggested to be capacitively coupled with only one surrounding rectangular ring, different from the previous 1D ZOR antennas commonly having several metal cells in line. The performance of the proposed antenna is simulated by a 3D field solver that inputs the sizes of the physical structure corresponding to the equivalent circuit designed to have ZOR at 2.4 GHz. Consequently, the resonance frequency, the gain and the antenna efficiency are observed 2.4 GHz, 5 dB and 98%, respectively. Besides, the important property of the proposed antenna is addressed as the combination of the low profile as an advantage of microstrip patch antennas, and the omni-directional field pattern typical of monopole antennas.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.36T no.4
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• pp.103-109
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• 1999

In this paper, we proposed to a new structure of T-shaped fed microstrip slot antenna using 2-layers dielectric material with a directional radiation characteristic. When the slot antenna of bi-directional radiation want to radiate only one direction, the reflector must be set up, but this antenna does'nt need set up reflector. T-shaped microstrip feed line is proposed for a better impedance matching to the microstrip slot antenna in a various range of slot widths. It was also found that the bandwidth of this antenna is proportional to the slot width. It was also found that the radiation resistance of this feed line structure is quite constant and low regardless to the slot width. We also analyzed this antenna by using the FDTD method, and calculating waves and electric field distribution in the time domain. we also are calculated return loss, VSWR, and radiation pattern in the frequency domain by Fourier transforming the time domain results, respectively. From the measured results, bandwidth was 34.8% in the center frequency. These results were in relatively good accordance with the calculated values.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.10
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• pp.1052-1059
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• 2003

In this paper, we proposed the directional coupler using two layer microstrip substrate which is improved coupling and isolation. Also, we notified a design method. Modified re-entrant mode coupler is the structure added to the aperture on the ground plane in order to improving the coupling value. And, by adding to slits on the floating conductor, this structure has good performance in isolation, VSWR according to S$\sub$11/, and phase difference. As a result, proposed re-entrant mode microstrip directional coupler has about 1.5 dB more higher coupling and 20 dB more higher isolation than conventional coupler. And because this coupler has good performance in phase difference, it can be used multi-section coupler.

• Journal of Advanced Navigation Technology
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• v.9 no.2
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• pp.147-155
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• 2005

In this paper, we propose that three uniform coplanar waveguides(CPWs), such as a conventional, finite grounded(FG), and grounded(G) CPWs, can be coupled with a $TE_{01{\delta}}$ mode dielectric resonator(DR) for a parallel resonant characteristic as a microstrip line coupled with the DR. Coupling characteristics have been investigated by placing the DR on a dielectric support above the CPWs and by moving the DR away from the center of a slot of the CPWs to the ground plane. FEM simulation(HFSS) results in terms of S-parameters agree well with measurement results. Finally, unloaded Q values of the DR coupled with the three uniform CPWs are compared with those of the DR coupled with a microstrip line. The comparison shows that the DR coupled with the three CPWs has higher unloaded Qs than that coupled with a microstrip line and that the GCPW case has the highest unloaded Qs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.6A
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• pp.648-656
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• 2007

This paper is about band pass filter, using Ceramics in the condition of center frequency 370Hz at milli-wave. The band pass filter is applied to Broadband Convergence Network, representing WLL(Wireless Local Loop) and LMDS(Local Multi-point Distribution Service). Sticking ceramic between strip line on a dielectric material substrate with which conductor's covers upper and basal surface, One will house the exterior by using structural resonance. In this Non Radiative Microstrip Line Filter structure, based upon simulations, generalized the two formulas finding resonant frequency of 1step ceramic resonator and bandwidth of 4step ceramic resonator. Also, As a result of experiment, using Network Analyzer, about created a experiment of structure based on the simulation result of 4-step ceramic resonator, It showed good characteristic of targeted bandwidth, comparing simulated result of 36.58GHz$\sim$37.650GHz with experimented result of 36.6GHz$\sim$37.65GHz.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.5
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• pp.33-39
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• 2021

In this study, we tried to find the correlation of the parameters and dual resonance of U-slot microstrip patch antenna with L-shaped Inset-feed structure and design broadband antenna using them. In the first step, we classified cases where dual resonance occurs through changes in antenna parameters that affect antenna performance. In the second step, we correlated each antenna parameter to the location and intensity of the resonance point, and 3 dB bandwidth. Next, antenna simulation confirmed the process of designing to have wide bandwidth using the correlation in the second step previously presented in the U-slot antenna case with narrow bandwidth. Finally, we fabricated a designed antenna and demonstrated the validity of antenna bandwidth broadening through the correlation analysis.