• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.21 no.12
• /
• pp.3277-3285
• /
• 1996

In this paper, w designed an opical power distribution device for application to an optical switching and an optical subscriber loop. We fabricated PSG thin film by LPCVD. Based on the measured index of fabricted thin film, rib-type waveguide was transformed to two-dimension by the effective index method and we simulated dispersion property to find asingle-mode condition. We found that the optimum design parameters of rib-type waveguide are:cladding layer of 3.mu.m, core layer of 3.mu.m, buffer layer of 10.mu.m, and core width of 4.mu.m. Each side of the guiding region was etched down to 4.mu.m to shape the core. We used these optimum parameters of the rib-type waveguide with branching angle of 0.5.deg. and simulted the Y-branch waveguide by the BPM simulation. Numerical loss in branching area was claculated to be 0.1581dB and equal to the total loss of the Y-branch. The loss of the fabricated Y-branch waveguide on PSG film ws 1.6dB at .lambda.=1.3.mu.m before annealing but was 1.2dB after annealing at 1000.deg. C for 10 minutes. Consequently, the loss of branching area from 3000.mu.m to 6000.mu.m in the z-direction was 0.8dB, and single-mode propagation was confirmed by measuring the near field pattern. For coupling the fabricated Y-branch waveguide with an optical fiber, we fabricated V-groove which was used as the upholder of optical fiber. An etching angle was 54.deg. and the width and depth of guiding groove was 150.mu.m, 70.mu.m, respectively. The optical fiber is inserted onto V-groove. Both the Y-branch and V-groove were connected through the index matching oil. Coupling loss after connecting Y-branch and the optical fiber on V-groove was 0.34dB and that after injecting index mateching oil was 0.14dB.

• ETRI Journal
• /
• v.27 no.6
• /
• pp.677-684
• /
• 2005

A phased array antenna was fabricated using four-element ferroelectric phase shifters with a coplanar waveguide (CPW) transmission line structure based on a $Ba_{0.6}Sr_{0.4}TiO_3(BST)/MgO$ structure. Epitaxial BST films were deposited on MgO (001) substrates by pulsed laser deposition. To attain the large differential phase shift and small losses for a ferroelectric CPW phase shifter, an impedance-matching-part adding technique between the effective transmission line and connecting cable was used. The return loss and insertion loss for this techniqueadapted BST CPW device were improved with respect to those for a normal BST CPW device. For an X-band phased array antenna system consisting of ferroelectric BST CPW phase shifters, power divider, dc block, patch antenna, and programmed dc power, the steering beam could be tilted by $15^{\circ}$ in either direction.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.25 no.1
• /
• pp.1-7
• /
• 1988

A new type broadband channel dropping filter which has a potential use as a millimeter-wave multiplexer has been realized by properly connecting 3-dB directional couplers and bandstop filters. 90\ulcorner3-dB directional couplers have been designed using two nonuniformly coupled dielectric image guides, while bandstop filters with Chebyshev passbands have been designed using dielectric image-guide grating structure. Effective dielectric constant method has been aplied to the image-guide dispersion analysis and to the design of bandstop gratings and 3-dB couplers. Experimental results in excellent agreement with computed responses are demonstrated.

• Korean Journal of Materials Research
• /
• v.12 no.4
• /
• pp.254-258
• /
• 2002

To realize channel cross-connecting in optical communications systems, a high speed optical matrix switch was fabricated using z-cut $LiNbO_3$. For switch fabrication was design bending structure and coupling length and four $2{\times}2$ directional couplers were integrated on one substrate far construction of a $4{\times}4$ switch. Single-mode optical waveguides were formed by Ti-diffusion at a wet $O_2$ atmosphere. Ti-diffusion profile, refractive index variation and waveguide morphology were analyzed by Prism coupler and optical microscopy, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.20 no.12
• /
• pp.2199-2205
• /
• 2016

In this paper, a design method for a coplanar waveguide (CPW)-fed 2-element quasi-Yagi antenna (QYA) is studied. A balun between CPW and coplanar strip (CPS) which feeds a planar dipole is implemented by connecting the one end of ground strips in a CPW to a signal strip. The antenna size is reduced by bent strip dipole and reflector, and an integrated balun. The proposed antenna was designed for the operation in a UHF radio frequency identification (RFID) band of 902-928 MHz, and the effects of various parameters such as dipole length, reflector length, distance between dipole and reflector, feed position were examined. The antenna with a size of $90mm{\times}80mm$ was fabricated on an FR4 substrate, and the experiment results reveal a frequency band of 885-942 MHz for a voltage standing wave ratio < 2, a gain > 4.3 dBi, and a front-to-back ratio > 7 dB over the frequency band for the UHF RFID.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.15 no.5
• /
• pp.108-115
• /
• 2016

In this paper, the array synthesis horn antenna was designed and measured a radiation power after connecting magnetron. The proposed antenna was designed on the basis of the $4{\times}4$ array synthesis horn antenna characteristics. For suppressing a back-lobe, 2 step short-stub structures were attached to synthesis horn aperture upper and lower. The designed antenna has FBR(Front to Back Ratio) of 39.7 dB. HPBW(Half Power Beam Width) of the E-plane and the H-plane are $8.86^{\circ}$ and $7.35^{\circ}$ each in the measurement. For measuring a radiation power of array antenna that use a magnetron, the waveguide adaptor was designed and connected magnetron with horn antenna. Also, microstrip line coupler that replace a dielectric material with an air gap was designed for measuring a high power. As a result, average radiation output power of the $4{\times}4$ array synthesis horn antenna that connect a four magnetrons had a 0.063W.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.35D no.6
• /
• pp.72-78
• /
• 1998

An optical modulator Ti:LiNbO$_3$optical waveguide and CPW electrode structure were fabricated. The optical modulator was packaged using components such as ferrules, dirmy LN block and glass, vibration and shock absorbption pad, and alumina feeder through processings of pigtailing. Au wire bonding, epoxing, SMA connecting, sealing. The electrical and optical characteristics were measured after packaging. The electrical properties of S$_{21}$ and S$_{11}$ were obtained as 9.8 GHz at -3 dB and -8.9dB at 14.4GHz, respectively. Optical waveguide prepared met requirements for a single mode at a 1550nm wavelength range. Insertion loss was 4.3dB at room temperature after packaging, and was varied 4.3~6.4dB at various temperatures, 5~45$^{\circ}C$. E-O bandwidth measurement showed 3dB optical response at 7.8GHz, which means that it is applicable for 10Gbps optical communicationon

• The Journal of the Acoustical Society of Korea
• /
• v.40 no.1
• /
• pp.31-37
• /
• 2021

In this paper, we design an acoustic meta-material silencer that operates at low frequency to reduce noise in duct. A high refractive index meta-material silencer is demonstrated with a combination of zigzag structured thin waveguide and helmholtz resonator, which reduces the speed of sound. Finite Element Method (FEM) analysis via thermo-viscous acoustic mesh is performed in order to calculate thermo-viscous dissipation in sub-wavelength waveguide. Sound power reflection, transmission and absorption coefficients are obtained utilizing 4-Microphone Method. The results show that cut-off frequency and transmission loss can be controlled through adjusting intervals of the zigzag structures. A wide-band acoustic silencer is also suggested by connecting meta-materials in series or parallel.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.22 no.1
• /
• pp.114-124
• /
• 2011

In this paper, we present a 2 GHz compact analog phase shifter with linear phase-tune characteristic. The compact phase shifter was designed base on a lumped all pass network and implemented using a ceramic substrate fabricated with thin-film technique. For a linear phase-tune characteristic, a capacitance of the varactor diode for a tuning voltage was linearized by connecting series capacitor and subsequently produced an almost linear capacitance change. The inductor and bias circuit in the all pass network was implemented using a spiral inductors for small size, which results in the size reduction to $4\;mm{\times}4\;mm$. In order to measure the phase shifter using the probe station, two CPW pads are included at the input and output. The fabricated phase shifter showed an insertion loss of about 4.2~4.7 dB at 2 GHz band and a total $79^{\circ}$ phase change for DC control voltage from 0 to 5 V, and showed linear phase-tune characteristic as expected in the design.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.23 no.6
• /
• pp.691-699
• /
• 2012

In this paper, we present a Vt-DRO with a low phase noise, which is achieved by improving the coupling structure between the dielectric resonator and microstrip line. The Vt-DRO is a closed-loop type and is composed of 3 blocks; dielectric resonator, phase shifter, and amplifier. We propose a mathematical estimation method of phase noise, using the group delay of the resonator. By modifying the coupling structure between the dielectric resonator and microstrip line, we achieved a group delay of 53 nsec. For convenience of measurement, wafer probes were inserted at each stage to measure the S-parameters of each block. The measured S-parameter of the Vt-DRO satisfies the open-loop oscillation condition. The Vt-DRO was implemented by connecting the input and output of the designed open-loop to form a closed-loop. As a result, the phase noise of the Vt-DRO was measured as -132.7 dBc/Hz(@ 100 kHz offset frequency), which approximates the predicted result at the center frequency of 5.3 GHz. The tuning-range of the Vt-DRO is about 5 MHz for tuning voltage of 0~10 V and the power is 4.5 dBm. PFTN-FOM is -31 dBm.