• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.2
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• pp.111-118
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• 2003

Notch Antenna is a travelling wave type antenna and can provide multioctave operation in phased arrays that scan over wide angle. In this paper, we designed a wideband E-plane phased array antenna using E-plane waveguide simulator which has a bandwidth of 3 : 1 and a scan volume of $\pm$45$^{\circ}$ in E-plane. We compared impedance of single antenna and infinite array antenna using equivalent circuit modeling. We analyzed full structure of 1$\times$9 phased array antenna and we evaluated active reflection coefficient with variation of beam scan angle through mutual coupling coefficient acquired from simulation and investigated the variation of antenna gain with variation of active element pattern as beam scan angle is varied.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.5
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• pp.444-449
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• 2003

In this paper, a PCB(Printed Circuit Board) antenna for IMT-2000 is designed and analyzed. The antenna has a helical structure with via-holes and lines on FR-4($\varepsilon$$\sub$${\gamma}$/=4.6 ) PCB, and the type of feeding is GCPW(Grounded Co-Planar Waveguide). Using HFSS of Ansoft, the antenna was designed and the measured results of frequency and radiation characteristic,3 with VSWR<2.0 are satisfied within operating frequency band of 1.920∼2.170 GHz. And it has resonating frequency of 2.045 GHz and a bandwidth of 321 MHz. The radiation gain of the antenna was measured to be -1 dBi.

• Journal of electromagnetic engineering and science
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• v.16 no.4
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• pp.248-253
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• 2016

Two substrate integrated waveguide (SIW)-based antennas for the application of software-defined radar are proposed and investigated herein. It is usually well known that SIWs are easily integrated, lightweight, have low insertion loss, and low interference levels compared to conventional microstrip structures. The primary function of the proposed antennas is to transmit continuous waves for indoor motion detection, with the lowest amount of loss and an appropriate amount of gain. Moreover, the results of this study show that the size of the antenna can be reduced significantly (i.e., by about 40%) by applying a meander line structure. The operating frequencies of the proposed antennas are both within the industrial, scientific, and medical band (i.e., 2.4-2.4835 GHz). Measured results of return loss are -16 dB and -20 dB at 2.435 GHz and 2.43 GHz, respectively, and the measured gain is 8.2 dBi and 5.5 dBi, respectively. Antenna design and verification are undertaken through commercially available full electromagnetic software.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.57-58
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• 2018

In this paper, we studied a design method for a quasi-Yagi antenna operating over a broad bandwidth covering the UHF RFID(902-928 MHz) and GNSS(1,164-1.605 MHz). The proposed antenna is composed of three elements(dipole, reflector, and director) and fed by a coplanar waveguide. To reduce its size, a balun is integrated inside the antenna, and the ends of both the dipole and reflector are bent. Broadband impedance matching was obtained by placing the director near to the dipole and loading a chip capacitor inside the antenna. The antenna, designed through simulations, was fabricated on an FR4 substrate with 0.8 mm thickness. The experiment results for the antenna characteristics agree very well with the simulation.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.1133-1136
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• 2002

We designed and fabricated a low local oscillation (LO) power V-band CPW mixer module using a CPW-to-waveguide transition technology for the application of millimeter-wave wireless communication systems. The mixer was designed using a unique gate mixing architecture to achieve simultaneously a low LO input power, a high conversion gain, and good LO-RF isolation characteristics. The fabricated mixer exhibited a high conversion gain of 2 dB at a low LO power of 0 dBm. For data transmission of the 60 ㎓ wireless LNA systems, we fabricated a CPW-to-waveguide converter module of WR-15 type and mounted the fabricated mixer in the converter module. The fabricated V-band mixer exhibited a higher conversion gain and a lower LO input power than other reported V-band mixers.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.1
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• pp.90-98
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• 1999

This paper presents a wideband single-balanced mixer using a diode which can be used in RF receiver of microwave measurement systems. For wideband characteristic, local oscillator(LO) signal is provided to diode with low loss using a coplanar waveguide-to-slotline balun. For high isolation characteristic radio frequency (RF) port and intermediate frequency (IF) port are designed using directional coupler. This mixer presents 30.5~31.17dB conversion loss whose flatness is within 1dB for 9 kHz~2.6 GHz wideband RF signal, and above 30 dB isolation for LO signal.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.5
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• pp.55-60
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• 2012

Longitudinal transmission-line modal theory is applied to analyze maximum power transfer in plasmonic grating-assisted directional couplers (P-GADC) based on silicon waveguide. By defining a coupling efficiency amenable to rigorous analytical solutions and interference between even and odd modes, the power exchange of TE modes as a function of propagation distance is evaluated. The numerical result reveals that maximum power transfer occurs at a grating period ${\Lambda}_{eq}=10.26{\mu}m$, in which the insertion loss of supermodes is equal to each other. That is, it is generally different from conventional phase-matching condition or minium gap condition of GADC.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.6
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• pp.81-89
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• 1996

Quantum RF impedance of SIS (superconductor insulator superconductor) junction has been analyzed by using through on tucker's quantum mixer theory in the frequency range form 80 GHz to 120 GHz. The embedding impedance of waveguide-type mixer mount and its equivalent circuit have been evaluated. From these evaluated results, the impedance matching efficiency between mixer mount embedding impedance and mixer port impedance of upper-side band and IF which were determined by augmented admittance matrix with given backshort position has been discussed in detail. It is found that the mixer with fixed backshort mount ahs a impedance matching efficiency about 80% at each port of mixer within 85GHz to 115GHz, which implys a conversion los of mixer would be good enough to be operated such a wide band frequency range. Therefore, the theoretical evaluated results show that our method can be used ot design the mixer mount without any mechanical tuning elements such a backshort or an E-plane tunners for wide band operation.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.4
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• pp.63-71
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• 2002

In this paper, we present microwave characteristics of traveling-wave photodetectors (TWPD) using the finite-difference time-domain method (FDTD). Current and voltage in the time domain are calculated by the FDTD. Also, characteristic impedance and propagation constant in frequency domain are obtained from the time-domain data. As the thickness of i-layer gets thicker and the waveguide width gets narrower, TWPD's show less microwave loss and higher velocity. The 50Ω impedance matching design is achieved for 2.4${\mu}{\textrm}{m}$ waveguide width and 1.2${\mu}{\textrm}{m}$ thickness of i-layer at 100 GHz.

• Korean Journal of Optics and Photonics
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• v.15 no.6
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• pp.503-510
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• 2004

We propose a novel vertical directional coupler switch using a vertical directional coupler with polarization independent coupling lengths employing the doublesided deep-ridge waveguide structure. This switch is composed of a switching operation induced section with symmetric structures and an extinction ratio enhanced section with asymmetric structures. We present design methods and examples for this switch with very short lengths and very high extinction ratios larger than 30 dB for both TE and TM modes in cases of both cross and bar states.