• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.1
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• pp.59-66
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• 2011

In this paper, a co-planar waveguide(CPW)-fed zeroth-order resonant(ZOR) antenna with an improved radiation efficiency was built and tested. The unit cell of the proposed antenna consists of a series metal-insulator-metal(MIM) capacitor and a shorted shunt stub inductor. In order to reduce the antenna size and to achieve the high radiation efficiency two shorted shunt stub arms bent by 90 degree were connected to the ground plane through the via. The proposed antenna consisting of two unit cells has an open ended composite right/left-handed(CRLH) transmission line structure. As a result the dominantly radiating parts of the antenna comes from shunt stub arms and vertical vias. The total size of the fabricated zeroth-order resonant antenna is $0.22\;{\lambda}_0{\times}0.22\;{\lambda}_0$. The measured gain and efficiency of the fabricated antenna have been enhanced by 3.07 dBi and 75 %, respectively, at the zeroth-order resonant frequency of 2.97 GHz.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.9
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• pp.12-20
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• 2013

In this paper, a co-planar waveguide(CPW) fed zeroth-order resonant(ZOR) antenna with frequency reconfigurable radiating structures is fabricated and measured. The unit cell of proposed antenna consists of a series metal-insulator-metal(MIM) capacitor and two shunt line inductors which are shorted through the via. The proposed antenna is designed based on a composite right/left-handed(CRLH) transmission line with two unit cells and it has open ended structure in order to radiate electromagnetic energy mainly on the shunt arm. In order to reduce the antenna size and to exhibit a frequency reconfigurable ability using diode switches four straight strips bent by 90 degrees are used as shunt inductors. The total size of fabricated antenna is $0.22{\lambda}_0{\times}0.16{\lambda}_0$ at zeroth-order resonant(ZOR) frequency. The measured maximum gain and bandwidth (VSWR ${\leq}2$) are 3.1 dBi and 56MHz at ZOR frequency of 2.97 GHz, respectively. This type of antenna can be applied to a frequency reconfigurable antenna system with triple bands.

• Journal of Advanced Navigation Technology
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• v.27 no.1
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• pp.57-62
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• 2023

This paper proposes a tri-band bandpass filter using dual-mode stepped-impedance resonators (SIRs) with parallel coupled structures. The proposed filter adopts U-shaped SIRs with open stubs and parallel coupled lines (PCLs) that have inter-digital and comb-line shorted ends. Two U-shaped SIRs with open stubs build the first and third passband, and the central PCL resonators build the second passband. Five resonators and coupling structures are theoretically analyzed to derive the scattering parameters of the proposed filter. A novel tri-band bandpass filter is designed and fabricated using the induced scattering parameters. The measured result of the fabricated tri-band bandpass filter shows a good agreement with the simulated one.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.8
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• pp.887-894
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• 2007

In this paper, design and fabrication of the LPF with controllable four transmission zeros using electric coupling and added open stub is presented. Pass-band of the LPF is GSM band, and two transmission zeros are generated by the electric coupling at the WiBro and S-DMB band, And the other two transmission zeros are generated by the open stub at the upper frequencies. Harmonic frequency of the stop-band is suppressed by the realization of the filter using quasi-lumped element with small parasitic values. $C_M$, which is the electric coupling element of the equivalent circuit, is realized by the distance control between the open stubs of the filter structure. The fabricated LPF used teflon substrate with relative permittivity of 2.6. And it has a size of $38{\times}20{\times}0.79 mm^3$, which is including a feed line. The measured 3 dB cut-off frequency is 1.55 GHz, and locations of the transmission zeros are 2.20, 2.43, 4.11 and 6.84 GHz, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.1 s.104
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• pp.60-66
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• 2006

In this paper, a circular microstrip patch antenna for switchable polarization is presented. For the switchable polarization, pairs of tuning stubs and two PIN diodes are utilized. By independently setting the PIN diodes on or off, the antenna produces either linear polarization or circular polarization. From the results, the -10 dB impedance bandwidths of 57.0 MHz($2.4\%$) and 50.0 MHz($2.1\%$) when operated in the linear polarization, and the 3 dB axial ratio bandwidth of $1.3\%$ with minimum of 0.2 and 0.9 dB in the circular polarization have been observed.

• Journal of Digital Convergence
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• v.12 no.4
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• pp.343-348
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• 2014

This paper suggested a theoretical approach and an implementation for the design of an unequal Wilkinson power divider with a high dividing ratio operating at two-frequencies. The T-section transmission lines and the two-section of Monzon's theory are proposed to operate a dual-band application. To achieve the high dividing ratio divider, the high impedance line using a T-shaped structure and low impedance lines with periodic shunt open stubs are implemented. For the validation of this divider, a dual-band power divider with a high dividing ratio of 5 is simulated and measured at 1 GHz and 2 GHz. The measured performances of the divider are in good agreements with simulation results.

• Journal of the Korea Concrete Institute
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• v.18 no.2 s.92
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• pp.161-168
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• 2006

An experimental investigation was conducted to examine the hysteretic behaviors of ultra-high strength concrete tied columns. The purpose of this study is to investigate the safety of ultra-high strength concrete columns with 100 MPa compressive strength for the requirement of ACI provisions. Eight 1/3 scaled columns were fabricated to simulate an 1/2 story of actual structural members with the cross section $300{\times}300mm$ and the aspect ratio 4. The main variables are axial load ratio, configurations and volumetric ratios of transverse reinforcement. The results show that the deformability of columns are affected by the configurations and volumetric ratios of transverse reinforcement. Especially, it has been found that the behavior of columns are affected by axial load ratio rather than the amounts and the configurations of transverse reinforcement. Consequently, to secure the ductile behavior of 100 MPa ultra-high strength concrete columns, ACI provisions for the requirement of transverse steel may considered axial load level and the details of transverse reinforcement.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.1
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• pp.1-7
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• 2016

In this paper, the compact CPW-fed slot antenna for WLAN applications is proposed. While the proposed antenna with size of only $20{\times}18{\times}1mm^3$ is consisted of double stub and folded slot, the antenna for 2.4 GHz band and 5 GHz band is designed and fabricated with optimized parameters obtained by simulation. Proposed antenna is fabricated with FR-4 substrate to the thickness of 1.0 mm. By obtaining the measured return loss level of < -10 dB at dual-band, we showed that it is operated as antenna for WLAN applications, and then it is also expected to be usable as antenna for RFID.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.12
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• pp.1447-1453
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• 2010

In this paper, the design and the fabrication of dual-band bandpass filter using two dual-mode resonators is presented. Dual-mode resonator using a short stub is miniaturized by inter-digital capacitor and stepped impedance. Two dual mode resonators are designed to have different resonant frequencies, one for the lower passband and the other for the upper passband. Transmission zero is positioned at low or high rejection bands with a sharp skirt characteristic. Dual-band operation can be achieved using dual feeding structure. For WLAN, the proposed filter at 2.45/5.25 GHz is designed and fabricated. The size of the filter is as compact as 1$10.83\;mm{\times}5.3\;mm$.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.5
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• pp.69-74
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• 2010

In this paper, we proposed a compact arbitrary dual-band band-stop filter using CRLH transmission line. The proposed filter used CRLH transmission line as stub and it developed dual-band band-stop characteristics using non-linear phase response of CRLH transmission line. The size of proposed filter is compact. And it can control arbitrary dual stop band. In this paper, designed band-stop filter at GPS band and ISM band As result, the S(2,1) is about -30dB at GPS band and about -29dB at ISM band. The fabricated filter is very compact. Its dimension is 10mm*15mm.