• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.7
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• pp.72-76
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• 2008

In this paper, the several printed square loop antennas which modified monopole antennas are proposed. The proposed antennas are reduced about 20% physical size of antenna and miniaturized reactance value of impedance due to fold center part of the loop. They obtained omni-directional radiation patterns with broad bandwidth and feed method used coplanar waveguide to composed single planar. The proposed antenna bandwidth is about 900MHz($2.63{\sim}3.56GHz]$) resonance frequency on $VSWR{\le}2$. it can be sufficiency of S-DMB band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.1
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• pp.87-97
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• 1998

This paper describes an analysis of tunable characteristic for magnetically tunable E-plane type finline filter on a ferrite substrate. The proposed design is based on using of quarter wavelength transmission line for compensating the negative length transmission line of end K-inverters of E-plane type waveguide filters and the tunable characteristics of designed filters are analyzed. The analysis results of filter and inverter structure loaded with finline on a ferrite substrate are obtained using the edge based finite element method including higher order mode effects. The X-band experimental results for bilateral and unilateral finline magnetically tunable E-plane type waveguide filters agree well with the simulated data.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.55-56
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• 2017

In this paper, a wideband loop antenna is designed using a CPW feeding method for indoor digital TV applications. The proposed loop antenna consists of a square loop and two circular sectors which connect the loop with central feed points, and the CPW feed line is inserted in the lower circular sector. The CPW feed line is designed to match with the 75 ohm port impedance for DTV applications, and the ground slots are etched in order to improve the impedance matching in the middle frequency region. The optimized antenna is fabricated on FR4 substrate, and the experiment results show that it operates in the frequency band of 463-1,280 MHz for a VSWR < 2, which assures the operation in the DTV band.

• Current Optics and Photonics
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• v.4 no.4
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• pp.293-301
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• 2020

In this paper we propose and theoretically analyze a monolithic multiparametric sensor consisting of a superstructure of surface-relief waveguide Bragg gratings (WBGs), a micro-machined diaphragm, and a cantilever beam. Diaphragms of two different configurations, namely circular and square, are designed and analyzed separately for pressure measurement. The square diaphragm is then selected for further study, since it shows relatively higher sensitivity compared to the circular one, as it incurs more induced stress when any pressure is applied. The cantilever beam with a proof mass is designed to enhance the sensitivity for acceleration measurement. A unique mathematical method using coupled-mode theory and the transfer-matrix method is developed to design and analyze the shift in the Bragg wavelength of the superstructure configuration of the gratings, due to simultaneously applied pressure and acceleration. The effect of temperature on the wavelength shift is compensated by introducing another Bragg grating in the superstructure configuration. The measured sensitivities for pressure and acceleration are found to be 0.21 pm/Pa and 6.49 nm/g respectively.

• ETRI Journal
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• v.46 no.3
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• pp.404-412
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• 2024

We propose a method for increasing the bandwidth of a substrate-integrated-waveguide (SIW) cavity-backed antenna with taper-based micro-strip SIW transition feeding. For radio transmission, a circular slot is etched on top of the SIW cavity. For optimal antenna design, the slot is etched slightly away from the cavity center to generate circularly polarized waves. Simulations show a wide axial ratio bandwidth of 7.860% between 11.02 GHz and 11.806 GHz. Experimental results confirm a similar wide axial ratio bandwidth of 4.9% between 10.8 GHz and 11.35 GHz. An SIW feed from an inductive window excites the radiating circular slot, resulting in a simulated wide impedance range of 1.548 GHz (10.338 GHz-11.886 GHz) and bandwidth of 13.93%. Experimental results show a wide impedance of 2.08 GHz (10.2 GHz-12.08 GHz) and bandwidth of 18.84%. The SIW cavity-backed antenna creates a unidirectional pattern, leading to gains of 6.61 dBi and 7.594 dBi in simulations and experiments, respectively. The proposed antenna was fabricated on a Rogers RT/Duroid 5880 substrate, and the reflection coefficient, radiation patterns, and gains were tested and compared using a computer simulator. The developed broadband antenna seems suitable for X-band applications.

• Journal of IKEEE
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• v.28 no.1
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• pp.72-77
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• 2024

In this paper, a triple-mode frequency-tunable filter is proposed to meet the recent demands of various frequency bands of mobile communication services. This filter has a tunable structure that can adjust the resonance frequency using a variable capacitor. To improve the quality factor, a SIW(Substrate Integrated Waveguide) structure was introduced and a structure that induces three resonance modes was implemented through a circular hole located in the center. The change in electric field distribution and resonance frequency by the variable capacitor was simulated using HFSS, and the change in electric field distribution and resonance frequency of Triple Mode mode was confirmed.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.1125-1128
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• 2003

This paper presents the design method of a Colpitts type oscillator with coplanar waveguide(CPW) structures in the range of Ka-band frequency for transmitter and receiver modules. Series short stubs of CPW patterns provide inductances and capacitances in the range of Ka-band which can be expressed as a CLC-$\pi$ equivalent circuit. The experimentation has employed ro4003 substrates as a CPW substrate which has a dielectric constant of 3.38 and a signal and ground space of 100um. A method of momentum simulation for the CPW patterns has performed with an ADS software tool of Hewlett-Packard Corp. Inductance and capacitance circuits of a Colpitts oscillator was interconnected to a MESFET with CPW bend structures of including the input and output impedance matching circuits of the active transistor. Circuit parameters for impedance matching were determined through the network conversion to the equivalent length of CPW transmission lines by using T-network 1 $\pi$-network conversion circuit. A Colpitts oscillator was fabricated on the substrate of a area of 8.5mm x 17.4mm with a MESFET of Fujitsu FMM5704X and CPW series short stubs. The design suggested the possibility of realizing oscillators on a planar surface for the wireless system of tansmitter and receiver modules in the frequency range of 30GHz

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.1-4
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• 2002

The numerical alaysis of optical device, silicabased device, are presented. The purpose of this paper is to simulate and to design a 8-channel optical wavelength division multiplexer(OWDM) based on Mach-Zehnder Interferometer(MZI) with wavelength spacing between channels Δλ=0.8 nm at central wavelength λ=1.55 ${\mu}{\textrm}{m}$. In initial condition fur simulating, we assumed as follows. A channel waveguide is made from silica based P-doped SiO2 core layers in order to coupling with a fiber easily and its core dimension was 6 ${\mu}{\textrm}{m}$$\times$6 ${\mu}{\textrm}{m}$. The core and clad index of channel waveguide were 1.455 and 1.444, separately, at λ=1.55 ${\mu}{\textrm}{m}$. Where, the separation between channel waveguides in coupling region was 3 ${\mu}{\textrm}{m}$. As a result of analysis, a group mode index of channel waveguide was 1.4498370, was gained by Hermite-Gaussian Method(HGM). Also, the channel spacing was determined by the waveguide arm length difference and was Δλ=0.8 nm as like a proposed condition. The central wavelength of a designed-multiplexer was activated about wavelength λ=1.55 ${\mu}{\textrm}{m}$, and we certificated that it can be used to 8-channel optical wavelength division multiplexer/demultiplexer.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.4
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• pp.185-190
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• 2015

In this paper we characterized and designed the waveguide antipodal finline transition at 57-65GHz frequency band in V-band for 5G mobile communication systems. Especially, we proposed the design method of spline taper for finline tapers by means of increasing curvature from linear taper. We could perform optimization more effectively by excluding improper regions for optimal performance from optimization using the method. Return losses and insertion losses of antipodal finline transitions were mainly affected by the taper shape of the finline. The resonances in the structure of the finline transition were the strongest enemies who deteriorate the performance of the transition. And we alleviated the resonances using semicircle shaped patch. The designed antipodal finline transition showed good performance as it showed less than -24.2dB of return loss and -0.24dB of insertion loss in the band(57-65GHz) which we suppose to use.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.1
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• pp.25-29
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• 2014

In this study, an optical PCB was proposed which can overcome the limitations of the conventional PCB, and a new structure with pluggable lens was considered for a high-efficient passive alignment. The structure was a lens-added optical waveguide for the improvement of misalignment between the lens and the waveguide in the alignment. Also, as it had a barrier-type structure to prevent the surface damage of the lens by desorption, the high-efficient passive alignment can be realized. The structure was designed by optimizing the simulation and the fabrication process of the pluggable lens structure was conducted using the repetitive photolithography and the thermal reflow. The optical waveguide with the lens-integrated pluggable interconnection was fabricated by the imprint process using the polydimethylsiloxane(PDMS) replica mold. Therefore, we confirmed the possibility of pluggable lens-added optical waveguide structure fabrication for high-efficient passive alignment.