• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.07b
• /
• pp.1187-1190
• /
• 2004

In this paper we analyze the reflection characteristics of a dielectric microstrip line with an open-end termination containing optically induced plasma region, which are analyzed by the assumption that the plasma is distributed homogeneously in the laser illumination. The characteristics impedances resulting from the presence of plasma are evaluated the transmission line model. To estimate theoretically the characteristic response of same systems in the time domain, the Fourier transformation method is evaluated. The reflection characteristics of time response in microwave systems have been calculated.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.4
• /
• pp.384-389
• /
• 2004

Crystal structure and microwave dielectric properties of Ba(Mg1/3Nb2/3) $O_3$ (BMN) ceramics were investigated. Ba(Mg1/3Nb2/3) $O_3$ has the 1:2 ordered hexagonal structure. The 1:2 ordering and relative density of specimens increased with small Mg deficiency(x). The variation of Q${\times}$ $f_{0}$ with Mg deficiency is very similar to that of 1:2 ordering and relative density. The highest Q${\times}$ $f_{0}$ achieved in this investigation is about 96,000 for Ba(Mg1/3Nb2/3) $O_3$. The improvement of Q${\times}$ $f_{0}$ with Mg-deficiency is related to the increase of degree of ordering and relative density of the specimen.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.11a
• /
• pp.46-50
• /
• 2003

Crystal structure and microwave dielectric properties of $Ba(Mg_{1/3-x}Nb_{2/3})O_3$ (BMN) ceramics were investigated. $Ba(Mg_{1/3}Nb_{2/3})O_3$ has the 1:2 ordered hexagonal structure. The 1:2 ordering and relative density of specimens increased with small Mg deficiency(x). The variation of Q-value with Mg deficiency is very similar to that of 1:2 ordering and relative density. The highest $Q{\times}f_0$ achieved in this investigation is about 96,000 for $Ba(Mg_{1/3-0.02}Nb_{2/3})O_3$. The improvement of Q-value with Mg-deficiency is related to the increase of degree of ordering and relative density of the specimen.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1997.04a
• /
• pp.239-244
• /
• 1997

A hair-pin shaped microstrip-line resonator and a dielectric resonator for injection-locked oscillators have been designed and fabricated for the comparative studying of their characteristics. In general, a commonly used dielectric resonator shows lower phase noise value than hair-pin resonator in the free-running mode. In the injection-locked mode, however, a hair-pin resonator is superior to the dielectric resonator; the wider tuning range, the 22% improved locking bandwidth, the lower noise effect, the short term stability, and the higher power level. The planar structure of a hair-pin shaped microstrip-line resonator will be easily applied to monolithic microwave integrated circuits.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.6
• /
• pp.1174-1179
• /
• 2009

In this paper we develop the characteristic of density on non-uniform plasma in different layer of the semiconductor with optically controlled microwave pulses. The transient response of the microwave pulses in different plasma layer has been evaluated by calculating the variation of the reflection function of dielectric microstrip lines. The lines has used under open-ended termination containing optically induced plasma region, which has illuminated a laser source. The characteristics impedances resulting from the presence of plasma are evaluated by the transmission line model. The analyzes the variation of transient response in a 0.01cm layer near the surface for frequency range from 1GHz to 128GHz. The diffusion length LD is larger than compared to the absorption depth $l/_{\alpha}l$. The variation of characteristic response in plasma layer with microwave pulses which has in deferentially localized has been evaluated analytically.

• Advances in nano research
• /
• v.14 no.6
• /
• pp.557-573
• /
• 2023

The rapid growth of zinc-oxide (ZnO) nanostructures (NSs) on woven carbon fiber (WCF) is reported in this study employing a microwave-aided chemical bath deposition process. The effects of different process parameters such as molar concentration, microwave duration and microwave power on morphologies and growth rate of the ZnO on WCF were studied. Furthermore, an attempt has been taken to study influence of different type of growth solutions on ZnO morphologies and growth rates. The surface functionalization of WCF fabrics is achieved by successful growth of crystalline ZnO on fiber surface in a very short duration through one-step microwave synthesis. The morphological, structural and compositional studies of ZnO-modified WCF are evaluated using field-emission scanning electron microscopy, X-ray diffraction and energy dispersive X-ray spectroscopy respectively. Good amount of zinc and oxygen has been seen in the surface of WCF. The presence of the wurtzite phase of ZnO having crystallite size 30-40 nm calculated using the Debye Scherrer method enhances the surface characteristics of WCF fabrics. The UV-VIS spectroscopy is used to investigate optical properties of ZnO-modified WCF samples by absorbance, transmittance and reflectance spectra. The variation of different parameters such as dielectric constants, optical conductivity, refractive index and extinction coefficient are examined that revealed the enhancement of optical characteristics of carbon fiber for wide applications in optoelectronic devices, carbon fiber composites and photonics.

• Proceedings of the KIEE Conference
• /
• 1993.11a
• /
• pp.181-184
• /
• 1993

Microwave characteristics of the system (Zr, Sn)$TiO_4$, ceramics within composition range X between 0.2 and 0.35 were investigated at 8GHz. For the improvement properties of (Zr, Sn)$TiO_4$, system, $Ta_2O_5$ and $WO_3$ addition in the range of 0.5 to 2.0wt% were investigated.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.7 no.2
• /
• pp.301-308
• /
• 1997

The LNT ceramics which has the large negative temperature coefficient of resonant frequency ($\tau_1$) were manufactured by varying the $TiO_2$ contents. The effects of secondary phase $TiO_2$ which was caused by excess $TiO_2$ on the microstructure, phase transformations and microwave dielectric properties in ($Li_{1/2}Nd_{1/2}$)$TiO_3$ binary system were studied by X-ray and SEM. In case of adding up to 5 mol% $TiO_2$ on LNT, the liquid phase $TiO_2$which was created in the grain boundary of LNT not only increased the bulk density but also caused the nonhomogeneous structure of LNT which reduced the microwave dielectric characteristics. But the temperature coefficient of resonant frequency was improved by the 10 mol% addition of $TiO_2$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.16 no.11
• /
• pp.987-993
• /
• 2003

We fabricated thick film monopole antennas using Mo-doped BiNbO$_4$ ceramics and investigated their electrical properties as a function of the Mo-doping concentration. Compared with undoped BiNbO$_4$ ceramics, 10 at.% Mo-doping improved microwave dielectric properties of ceramics by increased sintered density as well as decreased space charge density. Further increase in the Mo-doping concentration caused formation of Bi$_2$MoO$_{6}$ phases, resulting in deterioration of the microwave characteristics. The gain and bandwidth of the ceramic monopole antenna were also greatly affected by the Mo-doping concentration. When Mo-doping concentration was 10 at.%, highest gain of -0.7dBi with lowest bandwidth of 30% at 2.3GHz was obtained.

• Proceedings of the International Microelectronics And Packaging Society Conference
• /
• 2002.05a
• /
• pp.134-137
• /
• 2002

A new LTCC material in the $PbWO_4-TiO_2-B_2O_3-CuO$ system was developed. The developed material can be sintered at $850^{\circ}C$ and its dielectric properties are $\varepsilon_r=20-25, Q\timesf_o=30000~50000GHz$ , and $\tau_f=0.2~30ppm/^{\circ}C$, depending on the components moi ratio. Due to its low sintering temperature and microwave dielectric properties, the developed material can be used as a LTCC substrate for fabrication of multilayered microwave communication module set. In present study, using this material, tape casting condition was established. With this processing condition, a T-resonator was fabricated and its electrical properties were examined. Also, a 2-Pole band pass filter was fabricated and its frequency characteristics were compared with simulation results.