• Journal of the Microelectronics and Packaging Society
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• v.10 no.1
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• pp.51-56
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• 2003

Microwave dielectric properties of the $MgTiO_3-CaTiO_3$ ceramics were investigated for GPS antenna fabrication. (1-X) $MgTiO_3-X CaTiO_3$ ceramics with X=7 mol% sintered at $1400^{\circ}C$ exhibited can be dielectric constant of 20.6, the quality factor of 52,500 and the temperature coefficient of resonant frequency of -1.5 [ppm/$^{\circ}C$]. The results of $0.93MgTiO_3-0.070CaTiO_3$ ceramics with $P_2O_5$/ 0.6 wt% sintered at $1250^{\circ}C$ exhibited can be dielectric constant of 21, the quality factor of 58,000 and the temperature coefficient of resonant frequency of 2.6 [ppm/${\circ}C$]. The size, insertion loss, center frequency and band width of GPS antenna were $20.5{\times}20.5{\times}6[mm]$,-10(dB) and 1575.42(MHz) respectively. The insertion loss, center frequency and band width of the fabricated GPS antenna were -11 (dB), 1579(MHz) and 22(MHz) respectively. The center frequency was higher than design result, but other characteristics of GPS antenna were similar to the results of design result.

• Journal of the Korean Ceramic Society
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• v.34 no.6
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• pp.629-635
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• 1997

The effects of the annealing atmospheres(O2, N2) and sintering additives that Bi2O3 is a major composition on the microwave dielectric and sintering propertie of (1-x)CaTiO3-xLaAlO3 system were investigated. The annealing atmospheres and the increase of annealing time after sintering did not affect the relative dielectric constant($\varepsilon$r) and temperature coefficient of resonant frequency($\tau$f) of (1-x)CaTiO3-xLaAlO3 system. However, the Q.f0 values of (1-x)CaTiO3-xLaAlO3 were very sensitive to annealing atmospheres. As the annealing time increased under O2 atmosphere the Q.f0 values of (1-x)CaTiO3-xLaAlO3 enhanced untill 10 hrs in 0.3$\leq$x$\leq$0.6 region, but degraded over that time. The increasing rate of Q.f0 value increased wth increasing x. On the other hand, as the annealing time increased under N2 atmosphere the Q.f0 values were constant in x$\leq$0.6 region, increased gradually in x$\geq$0.7 region. When 0.97Bi2O3-0.03Al2O3 and 0.76Bi2O3-0.24NiO of 3wt% as sintering additives were added to (Ca0.5La0.5) (Ti0.5Al0.5)O3 (x=0.5) the sintering temperature of 1$600^{\circ}C$ was lowered to 140$0^{\circ}C$, and the relative dielectric constant($\varepsilon$r) and temperature coefficient of resonant frequency($\tau$f) were not nearly changed. The addition of 0.97Bi2O3-0.03Al2O3 and 0.76Bi2O3-0.24NiO of 3wt% to (Ca0.5La0.5)(Ti0.5Al0.5)O3 made the Q.f0 values to be lower about 15% and 34%, respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.152-155
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• 2000

This paper presents the characteristics of phase shifter which is operating at 2 GHz band and 12 GHz band. Two types of substrate stick with different dielectric constants are considered in these bands. Dielectric constants of microstrip feed crank line is 2.6. In the case of a small substrate stick with dielectric constant of 9 in the calculation, S21 phase is linearly varied at 1.98 GHz and 2.45 GHz, and variation of the shifting angle is about 20。. The angle of S21 phase shifting at 12 GHz band if calculated about 30。

• 전기의세계
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• v.28 no.4
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• pp.47-52
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• 1979

Total number of resonant modes in a microwave oven cavity may be maximized for a given frequency bandwidth to obtain more uniform power distribution by choosing proper size of the cavity. The total number of modes is calculated for a dielectrically loaded rectangular cavity and its size is suggested here for which the change in the number of modes is less sensitive to the change of dielectric layer thickness and its total number of modes is maximized in a given range of cavity sizes. A prove coupled rectangular cavity is constructed and the total existing modes are measured to see the change of modes depending on the dielectric layer thickness and the cavity size. Surface wave mode existing in the dielectric layer is confirmed by measuring Q and the input impedance of the cavity for this mode, which closely compares with the calculation.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.10
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• pp.51-59
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• 1998

($Na_{1/2}Ln_{1/2}$)$TiO_3$ceramics have a high relative dielectric constant and a positive temperature coefficient of resonant frequency ($\tau_f$)(where Ln represents a lanthanide: $La^{+3}$, $Pr^{+3}$, $Nd^{+3}$ and $Sm^{+3}$). On the other hand, $MgTiO_3$ ceramic has a high Qf value and a negative temperature coefficient. So We have investigated the microwave dielectric properties of $xMgTiO_3$-(1-x) ($Na_{1/2}Ln_{1/2}$)$TiO_3$. In these systems, there are no clues on solid-solution and secondary phase. There are mixed phases with $MgTiO_3$and ($Na_{1/2}Ln_{1/2}$)$TiO_3$ phases. Its dielectric characteristics (Qf, temperature coefficient and dielectric constant) are intermediate between ($Na_{1/2}Ln_{1/2}$)$TiO_3$ and $MgTiO_3$ and are predictable by the logarithmic mixing rule. The dielectric ceramic compositions temperature coefficient each approximates to zero at Ln=La, x=0.9, Ln=Pr, x=0.87, and Ln=Nd, x=0.84. At this time, there are Qf values in the range of 55,000 to 28,00GHz and relative dielectric constants in the range of 22 to 25.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.445-448
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• 2004

Radio frequency and microwave dielectric heating are well-known electroheating methods, used in industrial applications where non electrically conducting materials are to be heated, dried or otherwise processed. The major reason for considering this technique for any process is based on its unique ability to transfer heat into the volume of an electrically non conducting material such as insulator directly, rather than, via a surface. Conventional heating must first bring heat to the product surface and there after it depends on the physical characteristics and condition of the material as to how effectively this heat is transmitted into the mass. The product would suffer surface damage before the main body is adequately processed. Dielectric heating is applied to enhance conventional heating methods and to drastically shorten the required processing duration. Although the use of dielectric heating has been a well proven technique for several years in some industries, its application in the preheating of FRP has been limited by the insufficient experience. In this paper a method is described for uniform radio frequency heating of preheating of FRP.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.3 no.2 s.5
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• pp.69-74
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• 2004

In this work, A PLDRO (Phase Locked Dielectric Resonator Oscillator) which can be used for the wireless communication systems fur MMC(Microwave Micro Cell) and ITS wireless communication system is designed. A different approach to the PLDRO structure is applied for phase locking by dual phase lock loop structure. The proposed dual loop PLDRO generates the output power of 0 dBm at 18.7 GHz and has the characteristics of a phase noise of -80 dBc/Hz at 1kHz, -83 dBc/Hz at 10 kHz offset frequency from carrier frequency

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.300-304
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• 2002

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
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• 2001.11a
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• pp.146-150
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• 2001

Microwave model and high-frequency measurement of the ACF flip-chip interconnection was investigated using a microwave network analysis. S-parameters of on-chip and substrate were separately measured in the frequency range of 200 MHz to 20 GHz using a microwave network analyzer HP8510 and cascade probe. And the cascade transmission matrix conversion was performed. The same measurements and conversion techniques were conducted on the assembled test chip and substrate at the same frequency range. Then impedance values in ACF flip-chip interconnection were extracted from cascade transmission matrix. ACF flip chip interconnection has only below 0.1nH, and very stable up to 13 GHz. Over the 13 GHz, there was significant loss because of epoxy capacitance of ACF. However, the addition of SiO$_2$filler to the ACF lowered the dielectric constant of the ACF materials resulting in an increase of resonance frequency up to 15 GHz. High frequency behavior of metal Au stud bumps was investigated. The resonance frequency of the metal stud bump interconnects is higher than that of ACF flip-chip interconnects and is not observed at the microwave frequency band. The extracted model parameters of adhesive flip chip interconnects were analyzed with the considerations of the characteristics of material and the design guideline of ACA flip chip for high frequency applications was provided.

• Transactions on Electrical and Electronic Materials
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• v.10 no.4
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• pp.111-115
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• 2009

We present a study on the reflection of optically controlled microwave pulses from non uniform plasma layers in semiconductors. The transient response of the microwave pulses in different plasma layers has been evaluated by means of the reflection function of dielectric microstrip lines. The lines were used with an open-ended termination containing an optically induced plasma region, which was illuminated by a light source. The reflection characteristics impedance resulting from the presence of plasma is evaluated by means of the equivalent transmission line model. We have analyzed the variation of the transient response in a 0.01 cm layer with a surface frequency in the region of 128 GHz. In the reflection the variation of the diffusion length $L_D$ is large compared with the absorption depth $1/{\alpha}_l$. The variation of the characteristic response of the plasma layer with differentially localized pulses has been evaluated analytically. The change of the reflection amplitude has been observed at depths of 0.1 cm, 0.01 cm and $0.1{\times}10^{-5}$ cm respectively.